Antenna

Abstract

An objective of the present invention is to shorten the length of a stub. An antenna (100) comprises a dielectric substrate (1), a radiation electrode (2), a transmission line (3), a first connection conductor part (4a), a ground electrode (6), a short stub (5), and a second connection conductor part. The ground electrode (6) faces the radiation electrode (2), the transmission line (3), and the short stub (5) in the thickness direction (D1) of the dielectric substrate (1). The second connection conductor part connects the leading end of the short stub (5) with the ground electrode (6). The dielectric substrate (1) has a first region (110) in which the radiation electrode (2) is disposed, and a second region (120) in which at least a portion of the short stub (5) is disposed. The distance between the ground electrode (6) and a main surface (121) of the second region (120) of the dielectric substrate (1) in the thickness direction (D1) of the dielectric substrate (1) is shorter than the distance between the ground electrode (6) and the radiation electrode (2) in the thickness direction (D1) of the dielectric substrate (1).

Description

Antenna

[0001] The present invention generally relates to antennas, and more specifically to an antenna including a dielectric substrate.

[0002] Patent Document 1 discloses a patch antenna including a dielectric substrate, a planar ground, a planar antenna element, and a planar feed line.

[0003] In the patch antenna disclosed in Patent Document 1, the planar ground is provided on the first main surface of the dielectric substrate. The planar antenna element is provided on the second main surface of the dielectric substrate. The planar feed line is provided on the second main surface of the dielectric substrate. The planar feed line functions as a microstrip line together with the planar ground opposing each other across the dielectric substrate.

[0004] In the patch antenna disclosed in Patent Document 1, a stub is provided on the planar feed line.

[0005] Japanese Unexamined Patent Publication No. 2021-97328

[0006] In the patch antenna disclosed in Patent Document 1, the planar ground is provided on the first main surface of the dielectric substrate, and the open stub is provided on the second main surface of the dielectric substrate. Since the distance between the planar ground and the open stub is large, the characteristic impedance of the open stub increases, which leads to an increase in the length of the open stub. When the length of the stub increases, a part of the slab may be disposed between the planar antenna element and the planar ground in the thickness direction of the dielectric substrate, which in this case reduces the radiation efficiency of the antenna.

[0007] An object of the present invention is to provide an antenna capable of shortening the stub length.

[0008] An antenna according to one aspect of the present invention comprises a dielectric substrate, a radiating electrode, a transmission line, a first connecting conductor portion, a short stub, a ground electrode, and a second connecting conductor portion. The dielectric substrate has a first main surface and a second main surface. The radiating electrode is disposed on the first main surface of the dielectric substrate. The transmission line is disposed on the dielectric substrate and is spaced apart from the radiating electrode in the thickness direction of the dielectric substrate. The first connecting conductor portion is disposed on the dielectric substrate and connects the radiating electrode and the transmission line. The short stub is disposed on the dielectric substrate and branches off from the transmission line. The ground electrode is disposed on the second main surface of the dielectric substrate and faces the radiating electrode, the transmission line, and the short stub in the thickness direction of the dielectric substrate. The second connecting conductor portion is disposed on the dielectric substrate and connects the tip of the short stub to the ground electrode. The dielectric substrate has a first region where the radiating electrode is located, and a second region, which is different from the first region, where at least a portion of the short stub is located. The distance between the main surface of the second region of the dielectric substrate and the ground electrode in the thickness direction of the dielectric substrate is shorter than the distance between the radiating electrode and the ground electrode in the thickness direction of the dielectric substrate.

[0009] The antenna according to the above embodiment of the present invention makes it possible to shorten the stub length.

[0010] Figure 1 is a plan view of an antenna according to Embodiment 1. Figure 2 shows the same antenna and is a cross-sectional view taken along line II-II in Figure 1. Figure 3 is a side view of the main part of the same antenna as seen through. Figure 4 is a bottom view of the same antenna as seen through. Figure 5 is a perspective view of the main part of the same antenna as seen through. Figure 6 is a diagram illustrating the dimensions of the same antenna as seen through. Figure 7 is a diagram illustrating the dimensions of the same antenna as seen through. Figure 8 is a cross-sectional view of an antenna according to Embodiment 2. Figure 9 is a plan view of the main part of an antenna according to Embodiment 3. Figure 10 is a side view of the main part of the same antenna as seen through. Figure 11 is a cross-sectional view of an antenna according to Embodiment 4. Figure 12 is a cross-sectional view of an antenna according to Embodiment 5. Figure 13 is a cross-sectional view of an antenna according to Embodiment 6. Figure 14 is a cross-sectional view of an antenna according to Embodiment 7.

[0011] Embodiments 1 to 7 will be described below with reference to the drawings. The drawings referenced in Embodiments 1 to 7 below are schematic diagrams, and the size and thickness of the components shown in the drawings do not necessarily reflect the actual dimensions, nor do the ratios of size and thickness between components necessarily reflect the actual dimensional ratios. Furthermore, each drawing defines and represents a Cartesian coordinate system with three mutually orthogonal axes: the X, Y, and Z axes. The X, Y, and Z axes are all virtual axes, and the arrows indicating "X," "Y," and "Z" in the drawings are merely for illustrative purposes and do not represent actual objects.

[0012] (Embodiment 1) The antenna 100 according to Embodiment 1 will be described with reference to Figures 1 to 7.

[0013] The antenna 100 according to Embodiment 1, as shown in Figures 1 to 3, comprises a dielectric substrate 1, a radiating electrode 2, a transmission line 3, a first connecting conductor portion 4a, a short stub 5, a ground electrode 6, and a second connecting conductor portion 4b (see Figure 3). As shown in Figure 2, the dielectric substrate 1 has a first main surface 101 and a second main surface 102. The radiating electrode 2 is located on the first main surface 101 of the dielectric substrate 1. The transmission line 3 is located on the dielectric substrate 1. The transmission line 3 is spaced away from the radiating electrode 2 in the thickness direction D1 of the dielectric substrate 1. The first connecting conductor portion 4a is located on the dielectric substrate 1 and connects the radiating electrode 2 and the transmission line 3. The ground electrode 6 is located on the second main surface 102 of the dielectric substrate 1. The ground electrode 6 faces the radiating electrode 2, the transmission line 3, and the short stub 5 in the thickness direction D1 of the dielectric substrate 1. The short stub 5 is located on the dielectric substrate 1. The short stub 5 branches off from the transmission line 3. As shown in Figure 3, the second connecting conductor portion 4b is located on the dielectric substrate 1 and connects the tip 51 of the short stub 5 to the ground electrode 6. As shown in Figures 1 and 2, the dielectric substrate 1 has a first region 110 on which the radiating electrode 2 is located, and a second region 120 on which the short stub 5 is located, which is different from the first region 110. As shown in Figure 6, the distance L2 between the main surface 121 of the second region 120 of the dielectric substrate 1 and the ground electrode 6 in the thickness direction D1 of the dielectric substrate 1 is shorter than the distance L1 between the radiating electrode 2 and the ground electrode 6 in the thickness direction D1 of the dielectric substrate 1. In this embodiment, the bottom surface of the recess provided on the first main surface 101 of the dielectric substrate 1 constitutes the main surface 121 of the second region 120.

[0014] Furthermore, the antenna 100 according to Embodiment 1 further comprises a power supply electrode 8 and a third connecting conductor portion 4c, as shown in Figures 2 and 3. The power supply electrode 8 is located on the second main surface 102 of the dielectric substrate 1. In the thickness direction D1 of the dielectric substrate 1, the power supply electrode 8 is spaced apart from the transmission line 3. In a plan view from the thickness direction D1 of the dielectric substrate 1, the power supply electrode 8 is surrounded by the ground electrode 6 and spaced apart from the ground electrode 6, as shown in Figure 4. As shown in Figure 2, the third connecting conductor portion 4c connects the power supply electrode 8 and the transmission line 3.

[0015] Furthermore, the antenna 100 according to Embodiment 1 further comprises an open stub 7, as shown in Figures 1 to 3 and Figure 5. The open stub 7 is arranged on the dielectric substrate 1. The open stub 7 branches off from the transmission line 3. In this embodiment, as shown in Figures 2 and 5, the transmission line 3 includes a first transmission line 31 and a second transmission line 32. In this embodiment, the short stub 5 branches off from the first transmission line 31. Also, in this embodiment, the open stub 7 branches off from the second transmission line 32. In this embodiment, the first transmission line 31 and the second transmission line 32 are spaced apart in the thickness direction D1 of the dielectric substrate 1. The antenna 100 according to Embodiment 1 further comprises a fourth connecting conductor portion 4d that connects the first transmission line 31 and the second transmission line 32. The dielectric substrate 1 has a third region 130 (see Figures 1, 2, 5 and 6) where the open stub 7 is arranged.

[0016] Furthermore, in the antenna 100 according to Embodiment 1, as shown in Figures 2 and 3, the dielectric substrate 1 has a plurality of dielectric layers 9 to 19. In addition, the antenna 100 according to Embodiment 1 further comprises a plurality of conductive layers 39 to 49. In the antenna 100 according to Embodiment 1, the plurality of dielectric layers 9 to 19 and the plurality of conductive layers 39 to 49 are stacked.

[0017] The plurality of conductive layers 39 to 49 include a first conductive layer (conductive layer 49) including a radiating electrode 2, a second conductive layer (conductive layer 39) including a ground electrode 6, a third conductive layer (conductive layer 41) including a short stub 5, and a fourth conductive layer (conductive layer 40) including an open stub 7. The third conductive layer (conductive layer 41) includes the short stub 5 and a first transmission line 31. The fourth conductive layer (conductive layer 40) includes the open stub 7 and a second transmission line 32. In this embodiment, the plurality of conductive layers 39 to 49 correspond one-to-one with the plurality of dielectric layers 9 to 19. Each of the plurality of conductive layers 39 to 49 is formed, for example, by patterning a metal foil (e.g., copper foil) attached to the main surface of the corresponding dielectric layer among the plurality of dielectric layers 9 to 19.

[0018] Antenna 100 is used, for example, in electronic equipment. Electronic equipment is, for example, a communication device. Communication devices are, for example, mobile phones (e.g., smartphones), but are not limited to mobile phones; they may also be, for example, notebook personal computers, wearable devices (e.g., smartwatches), etc.

[0019] The following describes each component of the antenna 100 in more detail.

[0020] (1.1) Dielectric Substrate The dielectric substrate 1 is rectangular in shape, as shown in Figure 1, when viewed from the thickness direction D1 (see Figure 2) of the dielectric substrate 1 in a plan view. The dielectric substrate 1 is not limited to a rectangular shape when viewed from the thickness direction D1 (see Figure 2) of the dielectric substrate 1, but may be square in shape, for example.

[0021] As shown in Figures 2 and 3, the dielectric substrate 1 has a plurality of dielectric layers 9 to 19 (11 in the illustrated example). The plurality of dielectric layers 9 to 19 are stacked on the dielectric substrate 1.

[0022] Each of the dielectric layers 9 to 19 is made of, for example, a thermoplastic resin. The thermoplastic resin is, for example, a liquid crystal polymer. The thermoplastic resin is not limited to a liquid crystal polymer, but may also be, for example, PTFE (polytetrafluoroethylene). In this embodiment, two adjacent dielectric layers in the stacking direction of the dielectric layers 9 to 19 are self-adhered to each other, and no adhesive layer is interposed between two adjacent dielectric layers.

[0023] The thickness of each of the multiple dielectric layers 9 to 19 is, for example, between 10 μm and 120 μm.

[0024] (1.2) Multiple conductive layers In the antenna 100 according to Embodiment 1, as shown in Figures 2 and 3, the multiple conductive layers 39 to 49 correspond one-to-one with the multiple dielectric layers 9 to 19. In the antenna 100 according to Embodiment 1, the multiple conductive layers 39 to 49 and the multiple dielectric layers 9 to 19 are arranged in the order of conductive layer 39, dielectric layer 9, dielectric layer 10, conductive layer 40, dielectric layer 11, conductive layer 41, dielectric layer 12, conductive layer 42, dielectric layer 13, conductive layer 43, dielectric layer 14, conductive layer 44, dielectric layer 15, conductive layer 45, dielectric layer 16, conductive layer 46, dielectric layer 17, conductive layer 47, dielectric layer 18, conductive layer 48, dielectric layer 19, and conductive layer 49.

[0025] Each of the multiple conductive layers 39 to 49 is conductive. The material of each of the multiple conductive layers 39 to 49 includes, for example, copper.

[0026] The thickness of each of the multiple conductive layers 39 to 49 is, for example, 3 μm to 40 μm.

[0027] The multiple conductive layers 39 to 49 are formed in a predetermined pattern defined for each layer.

[0028] In this embodiment, a conductive layer 49 disposed on the first main surface 101 of the dielectric substrate 1 includes a radiating electrode 2. In this embodiment, a conductive layer 39 disposed on the second main surface 102 of the dielectric substrate 1 includes a ground electrode 6 and a power supply electrode 8. In this embodiment, a conductive layer 40 separated from the conductive layer 39 in the thickness direction D1 of the dielectric substrate 1 includes a second transmission line 32 and an open stub 7. In this embodiment, a conductive layer 41 separated from the conductive layer 40 in the thickness direction D1 of the dielectric substrate 1 includes a first transmission line 31 and a short stub 5.

[0029] (1.3) Radiation electrodes As shown in Figures 1 to 3, the radiation electrodes 2 are arranged on the first main surface 101 of the dielectric substrate 1. In a plan view from the thickness direction D1 of the dielectric substrate 1, as shown in Figure 1, the radiation electrodes 2 are, for example, rectangular in shape. In a plan view from the thickness direction D1 of the dielectric substrate 1, the radiation electrodes 2 are not limited to a rectangular shape, but may be, for example, square in shape. As shown in Figures 2 and 3, the radiation electrodes 2 are included in a conductive layer 49 formed by patterning a metal foil (for example, copper foil) attached to the main surface of one of the plurality of dielectric layers 9 to 19.

[0030] In the antenna 100 of this embodiment, a patch antenna element is formed by a radiating electrode 2, a portion of the ground electrode 6 that overlaps with the radiating electrode 2 in the thickness direction D1 of the dielectric substrate 1, and a portion of the dielectric substrate 1 between the radiating electrode 2 and the ground electrode 6 in the thickness direction D1 of the dielectric substrate 1.

[0031] The material of the radiating electrode 2 includes, for example, copper. The thickness of the radiating electrode 2 is, for example, 3 μm or more and 40 μm or less.

[0032] (1.4) Transmission line As shown in the diagram 2, the transmission line 3 is separated from the radiating electrode 2 in the thickness direction D1 of the dielectric substrate 1. In this embodiment, the transmission line 3 includes a first transmission line 31 and a second transmission line 32. In the transmission line 3 of this embodiment, the first transmission line 31 and the second transmission line 32 are separated in the thickness direction D1 of the dielectric substrate 1. The distance L31 (see Figure 6) between the first transmission line 31 and the ground electrode 6 in the thickness direction D1 of the dielectric substrate 1 is longer than the distance L32 (see Figure 6) between the second transmission line 32 and the ground electrode 6 in the thickness direction D1 of the dielectric substrate 1.

[0033] The materials of the first transmission line 31 and the second transmission line 32 each include, for example, copper. The thickness of the first transmission line 31 and the second transmission line 32 each is, for example, 3 μm or more and 40 μm or less.

[0034] The first transmission line 31 is included in the conductive layer 41 of a predetermined pattern (first predetermined pattern). In this embodiment, the first transmission line 31 is linear. The first transmission line 31 is formed, for example, by patterning a metal foil (e.g., copper foil) attached to the main surface of one of the plurality of dielectric layers 9 to 19. The first transmission line 31 is interposed between two adjacent dielectric layers 11 and 12 in the thickness direction D1 of the dielectric substrate 1.

[0035] The first transmission line 31 has a line width in the X-axis direction and a thickness in the thickness direction D1 (parallel to the Z-axis) of the dielectric substrate 1. In this embodiment, the line width of the first transmission line 31 is narrower than the width of the dielectric substrate 1 in the X-axis direction. The thickness of the first transmission line 31 is thinner than the thickness of each of the two dielectric layers 11 and 12. The thickness of the first transmission line 31 is, for example, 3 μm or more and 40 μm or less.

[0036] The second transmission line 32 is included in the conductive layer 40 of a predetermined pattern (second predetermined pattern). In this embodiment, the second transmission line 32 is linear. The second transmission line 32 is formed, for example, by patterning a metal foil (e.g., copper foil) attached to the main surface of one of the plurality of dielectric layers 9 to 19. The second transmission line 32 is interposed between two adjacent dielectric layers 10 and 11 in the thickness direction D1 of the dielectric substrate 1.

[0037] The second transmission line 32 has a line width in the X-axis direction and a thickness in the thickness direction D1 (parallel to the Z-axis) of the dielectric substrate 1. In this embodiment, the line width of the second transmission line 32 is narrower than the width of the dielectric substrate 1 in the X-axis direction. In this embodiment, the line width of the second transmission line 32 is the same as the line width of the first transmission line 31. "The line width of the second transmission line 32 is the same as the line width of the first transmission line 31" is not limited to the case where the line width of the second transmission line 32 is 100% of the line width of the first transmission line 31, but is not limited to the case where the line width of the second transmission line 32 is within the range of 90% to 110% of the line width of the first transmission line 31. The thickness of the second transmission line 32 is thinner than the thickness of each of the two dielectric layers 10 and 11. The thickness of the second transmission line 32 is, for example, 3 μm to 40 μm.

[0038] In this embodiment, the second transmission line 32 is separated from the first transmission line 31 in the thickness direction D1 of the dielectric substrate 1. Also, in this embodiment, the first transmission line 31 and the second transmission line 32 overlap when viewed from a plan view from the thickness direction D1 of the dielectric substrate 1.

[0039] (1.5) First connecting conductor section, second connecting conductor section, third connecting conductor section and fourth connecting conductor section As shown in Figure 2, the first connecting conductor section 4a is arranged on the dielectric substrate 1 and connects the radiating electrode 2 and the transmission line 3. More specifically, the first connecting conductor section 4a is arranged across eight dielectric layers 12 to 19 out of a plurality of dielectric layers 9 to 19 (11 in the illustrated example) on the dielectric substrate 1 and connects the radiating electrode 2 and the first transmission line 31. The first connecting conductor section 4a is conductive. In this embodiment, as shown in Figures 2 and 3, the first connecting conductor section 4a has seven conductive layers 42 to 48 and eight connecting conductors V12 to V19. Of the seven connecting conductors V12 to V19, the connecting conductor V19 in contact with the radiating electrode 2 functions as the feed point of the antenna 100.

[0040] Each of the seven conductive layers 42 to 48 of the first connecting conductor portion 4a is made of, for example, copper. The thickness of each of the seven conductive layers 42 to 48 is, for example, 3 μm or more and 40 μm or less. The seven conductive layers 42 to 48 of the first connecting conductor portion 4a correspond one-to-one with the seven dielectric layers 12 to 18. Each of the seven conductive layers 42 to 48 of the first connecting conductor portion 4a is formed by patterning a copper foil attached to the main surface of the corresponding dielectric layer among the seven dielectric layers 12 to 18.

[0041] Each of the eight connecting conductors V12 to V19 of the first connecting conductor section 4a includes, for example, copper, a copper-tin alloy, and a resin. The eight connecting conductors V12 to V19 of the first connecting conductor section 4a correspond one-to-one with the eight dielectric layers 12 to 19. Each of the eight connecting conductors V12 to V19 of the first connecting conductor section 4a is formed by filling the via holes formed in the corresponding dielectric layer among the eight dielectric layers 12 to 19 with a conductive paste containing copper, a low-melting-point metal (for example, tin), and a resin, and heating it, with the via holes being blocked by a portion of the copper foil.

[0042] The second connecting conductor portion 4b is arranged on the dielectric substrate 1 as shown in FIG. 3, and connects the short stub 5 and the ground electrode 6. More specifically, the second connecting conductor portion 4b is arranged across three dielectric layers 9 to 11 among the plurality of (11 in the illustrated example) dielectric layers 9 to 19 of the dielectric substrate 1, and connects the tip 51 of the short stub 5 and the ground electrode 6. The second connecting conductor portion 4b includes a connecting electrode 401 included in the conductive layer 40, and three connecting conductors V9 to V11. Note that the conductive layer 40 includes a plurality of conductor portions. The plurality of conductor portions include the open stub 7 and the connecting electrode 401.

[0043] The material of the connecting electrode 401 of the second connecting conductor portion 4b includes copper, for example. The thickness of the conductive layer 40 including the connecting electrode 401 is, for example, 3 µm or more and 40 µm or less. The conductive layer 40 corresponds to one dielectric layer 10 among the plurality of dielectric layers 9 to 19. The conductive layer 40 is formed by patterning a copper foil attached to the main surface of the dielectric layer 10.

[0044] Each of the three connecting conductors V9 to V11 of the second connecting conductor portion 4b includes, for example, copper, a copper-tin alloy, and a resin. The three connecting conductors V9 to V11 of the second connecting conductor portion 4b correspond one-to-one to the three dielectric layers 9 to 11. Each of the three connecting conductors V9 to V11 of the second connecting conductor portion 4b is formed in such a manner that: after a via hole formed in the corresponding dielectric layer among the three dielectric layers 9 to 11 is blocked by a part of a copper foil, the via hole is filled with a conductive paste containing copper, a low-melting-point metal (e.g., tin) and a resin, and then heated.

[0045] The third connecting conductor portion 4c is arranged on the dielectric substrate 1 as shown in FIG. 2, and connects the feeding electrode 8 and the transmission line 3. More specifically, the third connecting conductor portion 4c is arranged across two dielectric layers 9 and 11 among the plurality of (11 in the illustrated example) dielectric layers 9 to 19 of the dielectric substrate 1, and connects the feeding electrode 8 and the second transmission line 32. The third connecting conductor portion 4c includes two connecting conductors V9 and V10.

[0046] Each of the two connection conductors V9 and V10 of the third connection conductor portion 4c contains, for example, copper, a copper-tin alloy, and a resin. The two connection conductors V9 and V10 of the third connection conductor portion 4c correspond one-to-one to the two dielectric layers 9 and 10. Each of the two connection conductors V9 and V10 of the third connection conductor portion 4c is formed in a state where the via hole formed in the corresponding dielectric layer among the two dielectric layers 9 and 10 is blocked by a part of copper foil, and is formed by filling the via hole with a conductive paste containing copper, a low-melting-point metal (e.g., tin) and a resin, and then heating the filled via hole.

[0047] As shown in FIG. 2, the fourth connection conductor portion 4d is disposed on the dielectric substrate 1, and connects the first transmission line 31 and the second transmission line 32. More specifically, the fourth connection conductor portion 4d penetrates one dielectric layer 11 among the plurality (11 in the illustrated example) of dielectric layers 9 to 19 of the dielectric substrate 1, and connects the first transmission line 31 and the second transmission line 32. The fourth connection conductor portion 4d has electrical conductivity. In the present embodiment, as shown in FIG. 2 and FIG. 3, the fourth connection conductor portion 4d includes a connection conductor V11.

[0048] The connection conductor V11 of the fourth connection conductor portion 4d contains, for example, copper, a copper-tin alloy, and a resin. The connection conductor V11 of the fourth connection conductor portion 4d is formed in a state where the via hole formed in the corresponding dielectric layer 11 among the plurality of dielectric layers 9 to 19 is blocked by a part of copper foil, and is formed by filling the via hole with a conductive paste containing copper, a low-melting-point metal (e.g., tin) and a resin, and then heating the filled via hole.

[0049] (1.6) Ground Electrode As shown in Figures 2 and 4, the ground electrode 6 is located on the second main surface 102 of the dielectric substrate 1. In a plan view from the thickness direction D1 of the dielectric substrate 1, the outer edge of the ground electrode 6 is, for example, rectangular along the outer edge of the dielectric substrate 1. As shown in Figure 1, in a plan view from the thickness direction D1 of the dielectric substrate 1, the ground electrode 6 is larger than the radiating electrode 2. In this embodiment, in a plan view from the thickness direction D1 of the dielectric substrate 1, the radiating electrode 2 is located inside the outer edge of the ground electrode 6. In a plan view from the thickness direction D1 of the dielectric substrate 1, the ground electrode 6 is located inside the outer edge of the dielectric substrate 1. As shown in Figure 4, the ground electrode 6 has an opening 62 that exposes the power supply electrode 8. The ground electrode 6 is conductive. The ground electrode 6 is contained in a conductive layer 39 formed by patterning copper foil attached to the main surface of the dielectric layer 9.

[0050] In an antenna, the capacitance formed between the radiating electrode and the ground electrode also affects the antenna characteristics. In this embodiment, in order to reduce the capacitance formed between the radiating electrode 2 and the ground electrode 6, as shown in Figure 2, the radiating electrode 2 is placed on the first main surface 101 of the dielectric substrate 1, and the ground electrode 6 is placed on the second main surface 102 of the dielectric substrate 1, thereby increasing the distance between the radiating electrode 2 and the ground electrode 6.

[0051] In this embodiment, in a plan view from the thickness direction D1 of the dielectric substrate 1, the ground electrode 6 surrounds the power supply electrode 8 (see Figures 2 and 4). The ground electrode 6 and the power supply electrode 8 are spaced apart from each other.

[0052] In this embodiment, as shown in Figures 2 and 3, the ground electrode 6 faces the radiating electrode 2, the transmission line 3, the short stub 5, and the open stub 7 in the thickness direction D1 of the dielectric substrate 1.

[0053] (1.7) Power supply electrode As shown in Figures 2 and 4, the power supply electrode 8 is arranged on the second main surface 102 of the dielectric substrate 1. In this embodiment, the power supply electrode 8 is circular in shape when viewed from the thickness direction D1 of the dielectric substrate 1. In this embodiment, the entire power supply electrode 8 overlaps with a part of the radiating electrode 2 when viewed from the thickness direction D1 of the dielectric substrate 1.

[0054] (1.8) Short Stub As shown in Figures 1 and 3, the short stub 5 is located on the dielectric substrate 1. The short stub 5 branches off from the transmission line 3 as shown in Figures 1 and 5. The short stub 5 is a stub whose tip is short-circuited to ground. In this embodiment, the short stub 5 protrudes from the transmission line 3 in the linewidth direction of the transmission line 3 (in this embodiment, the direction parallel to the X-axis). More specifically, in this embodiment, the first transmission line 31 is located along one direction (in this embodiment, the direction parallel to the Y-axis) perpendicular to the thickness direction D1 (in this embodiment, the direction parallel to the Z-axis) of the dielectric substrate 1, and the short stub 5 protrudes from the first transmission line 31 in the linewidth direction of the first transmission line 31 (in this embodiment, the direction parallel to the X-axis). In this embodiment, the linewidth direction of the short stub 5 is along the Y-axis. The short stub 5 is seamlessly connected to the first transmission line 31. As shown in Figures 3 and 5, the tip 51 of the short stub 5 is connected to the ground electrode 6 via the second connecting conductor portion 4b.

[0055] In this embodiment, the thickness of the short stub 5 is the same as the thickness of the first transmission line 31. Also, in this embodiment, the line width of the short stub 5 excluding the tip 51 is the same as the line width of the first transmission line 31, but it may be different from the line width of the first transmission line 31. In this embodiment, among the plurality of conductive layers 39 to 49, conductive layer 41 includes the first transmission line 31 and the short stub 5.

[0056] In this embodiment, the length of the short stub 5 is shorter than half the length of the dielectric substrate 1 in the X-axis direction.

[0057] (1.9) Open Stub As shown in Figures 1 and 3, the open stub 7 is located on the dielectric substrate 1. The open stub 7 branches off from the transmission line 3. The open stub 7 means a stub with an open tip. "Open tip" means that the tip of the stub is not connected to any other conductor. In this embodiment, the open stub 7 protrudes from the transmission line 3 in the line width direction of the transmission line 3 (in this embodiment, in the direction parallel to the X-axis). More specifically, in this embodiment, the second transmission line 32 is located along one direction (in this embodiment, in the direction parallel to the Y-axis) perpendicular to the thickness direction D1 (in the direction parallel to the Z-axis) of the dielectric substrate 1, and the open stub 7 protrudes from the connection pad 320 (see Figures 2 and 5) with the fourth connecting conductor portion 4d in the second transmission line 32 and extends in the line width direction of the second transmission line 32 (in this embodiment, in the direction parallel to the X-axis). In this embodiment, the open stub 7 is seamlessly connected to the second transmission line 32. As shown in Figure 3, the tip 71 of the open stub 7 is not connected to any other conductors and is covered by two dielectric layers 10 and 11.

[0058] In this embodiment, in a plan view from the thickness direction D1 of the dielectric substrate 1, the open stub 7 does not overlap with the short stub 5. Also, in this embodiment, as shown in Figure 1, in a plan view from the thickness direction D1 of the dielectric substrate 1, the open stub 7 protrudes from the transmission line 3 on the opposite side from the short stub 5. Furthermore, in this embodiment, in a plan view from the thickness direction D1 of the dielectric substrate 1, the open stub 7 is separated from the short stub 5 in the direction along the Y axis.

[0059] In this embodiment, the thickness of the open stub 7 is the same as the thickness of the second transmission line 32. Also, in this embodiment, the line width of the open stub 7 is the same as the line width of the second transmission line 32 excluding the connection pad 320. In this embodiment, as shown in Figure 2, among the plurality of conductive layers 39 to 49, conductive layer 40 includes the second transmission line 32 and the open stub 7.

[0060] In this embodiment, the length of the open stub 7 is shorter than half the length of the dielectric substrate 1 in the X-axis direction.

[0061] (2) First, second, and third regions of the dielectric substrate In the antenna 100, as shown in Figure 2, the thickness of the second region 120 on the dielectric substrate 1 where the short stub 5 is located is thinner than the thickness of the first region 110 on the dielectric substrate 1 where the radiating electrode 2 is located. Also, in the antenna 100, the thickness of the second region 120 on the dielectric substrate 1 is thinner than the thickness of the third region 130 on the dielectric substrate 1 where the open stub 7 is located. Also, in this embodiment, the thickness of the third region 130 on the dielectric substrate 1 is thinner than the thickness of the first region 110 on the dielectric substrate 1. In the antenna 100, as shown in Figures 3 and 7, in the thickness direction D1 of the dielectric substrate 1, the distance L56 between the short stub 5 and the ground electrode 6 is longer than the distance L76 between the open stub 7 and the ground electrode 6.

[0062] As shown in Figure 2, the first region 110 of the dielectric substrate 1 has a main surface 111 on the side opposite to the ground electrode 6. The second region 120 of the dielectric substrate 1 has a main surface 121 on the side opposite to the ground electrode 6. The third region 130 of the dielectric substrate 1 has a main surface 131 on the side opposite to the ground electrode 6. In a plan view from the thickness direction D1 of the dielectric substrate 1, the first region 110, the second region 120, and the third region 130 are arranged in the order of first region 110, second region 120, and third region 130 in a direction parallel to the Y axis.

[0063] In this embodiment, the thickness of the first region 110 of the dielectric substrate 1 is the thickness between the second main surface 102 of the dielectric substrate 1 and the main surface 111 of the first region 110, and is the total thickness of the plurality of dielectric layers 9 to 19. The thickness of the second region 120 of the dielectric substrate 1 is the thickness between the second main surface 102 of the dielectric substrate 1 and the main surface 121 of the second region 120, and is the total thickness of three dielectric layers 9 to 12 out of the plurality of dielectric layers 9 to 19. The thickness of the third region 130 of the dielectric substrate 1 is the thickness between the second main surface 102 of the dielectric substrate 1 and the main surface 131 of the third region 130, and is the total thickness of seven dielectric layers 9 to 15 out of the plurality of dielectric layers 9 to 19.

[0064] In this embodiment, the main surface 121 of the second region 120 of the dielectric substrate 1 is in contact with a medium (in this embodiment, air) having a relative permittivity smaller than the relative permittivity of the dielectric material of the dielectric substrate 1.

[0065] (3) The antenna 100 according to the first embodiment comprises a dielectric substrate 1, a radiating electrode 2, a transmission line 3, a first connecting conductor portion 4a, a short stub 5, a ground electrode 6, and a second connecting conductor portion 4b. The dielectric substrate 1 has a first main surface 101 and a second main surface 102. The radiating electrode 2 is located on the first main surface 101 of the dielectric substrate 1. The transmission line 3 is located on the dielectric substrate 1. The transmission line 3 is spaced away from the radiating electrode 2 in the thickness direction D1 of the dielectric substrate 1. The first connecting conductor portion 4a is located on the dielectric substrate 1 and connects the radiating electrode 2 and the transmission line 3. The short stub 5 is located on the dielectric substrate 1. The short stub 5 branches off from the transmission line 3. The ground electrode 6 is located on the second main surface 102 of the dielectric substrate 1. The ground electrode 6 faces the radiating electrode 2, the transmission line 3, and the short stub 5 in the thickness direction D1 of the dielectric substrate 1. The second connecting conductor portion 4b is located on the dielectric substrate 1 and connects the tip 51 of the short stub 5 to the ground electrode 6. The dielectric substrate 1 has a first region 110 on which the radiating electrode 2 is located, and a second region 120 on which the short stub 5 is located, which is different from the first region 110. The distance L2 between the main surface 121 of the second region 120 of the dielectric substrate 1 and the ground electrode 6 in the thickness direction D1 of the dielectric substrate 1 is shorter than the distance L1 between the radiating electrode 2 and the ground electrode 6 in the thickness direction D1 of the dielectric substrate 1.

[0066] With the above configuration, it is possible to shorten the stub length. More specifically, with the above configuration, the distance L5 (see Figure 2) between the main surface 121 of the second region 120 in the thickness direction D1 of the dielectric substrate 1 and the short stub 5 becomes shorter, and the effective relative permittivity around the short stub 5 becomes smaller, so the characteristic impedance of the short stub 5 becomes higher, and it becomes possible to shorten the stub length of the short stub 5.

[0067] Furthermore, in the antenna 100 according to Embodiment 1, the short stub 5 is located within the second region 120 of the dielectric substrate 1.

[0068] With the above configuration, the short stub 5 can be protected by the dielectric substrate 1.

[0069] Furthermore, the antenna 100 according to Embodiment 1 further comprises an open stub 7. The open stub 7 is arranged on the dielectric substrate 1 and branches off from the transmission line 3. The dielectric substrate 1 further has a third region 130. The third region 130 is different from the first region 110 and the second region 120. The open stub 7 is arranged in the third region 130. The ground electrode 6 faces the radiating electrode 2, the transmission line 3, the short stub 5, and the open stub 7 in the thickness direction D1 of the dielectric substrate 1. The distance L3 between the main surface 131 of the third region 130 of the dielectric substrate 1 and the ground electrode 6 in the thickness direction D1 of the dielectric substrate 1 is longer than the distance L2 between the main surface 121 of the second region 120 of the dielectric substrate 1 and the ground electrode 6 in the thickness direction D1 of the dielectric substrate 1.

[0070] According to the above configuration, the distance between the main surface 131 of the third region 130 in the thickness direction D1 of the dielectric substrate 1 and the open stub 7 can be increased, and the effective relative dielectric constant around the open stub 7 increases, so the characteristic impedance of the open stub 7 decreases, making it possible to shorten the stub length of the open stub 7.

[0071] Furthermore, in the antenna 100 according to Embodiment 1, the distance L56 between the short stub 5 and the ground electrode 6 in the thickness direction D1 of the dielectric substrate 1 is longer than the distance L76 between the open stub 7 and the ground electrode 6.

[0072] With the above configuration, the characteristic impedance of the short stub 5 can be increased while the characteristic impedance of the open stub 7 can be decreased, making it possible to shorten the stub length of both the short stub 5 and the open stub 7.

[0073] Furthermore, in the antenna 100 according to Embodiment 1, the dielectric substrate 1 has a plurality of dielectric layers 9 to 19, and the plurality of dielectric layers 9 to 19 are stacked.

[0074] With the above configuration, it is possible to change the antenna characteristics by changing the number of dielectric layers.

[0075] Furthermore, the antenna 100 according to Embodiment 1 further comprises a plurality of conductive layers 39 to 49. In the antenna 100, a plurality of dielectric layers 9 to 19 and a plurality of conductive layers 39 to 49 are stacked. The plurality of conductive layers 39 to 49 include a first conductive layer (conductive layer 49) including a radiating electrode 2, a second conductive layer (conductive layer 39) including a ground electrode 6, and a third conductive layer (conductive layer 40) including a short stub 5.

[0076] With the above configuration, it becomes possible to improve the reproducibility of the distance L1 between the ground electrode 6 and the radiating electrode 2, and the distance L56 between the ground electrode 6 and the short stub 5.

[0077] Furthermore, in the antenna 100 according to Embodiment 1, each of the materials of the plurality of dielectric layers 9 to 19 includes a thermoplastic resin.

[0078] According to the above configuration, it becomes possible to stack multiple dielectric layers 9 to 19 without an adhesive layer, thereby enabling the dielectric substrate 1 to be made thinner.

[0079] Furthermore, in the antenna 100 according to Embodiment 1, the thermoplastic resin includes a liquid crystal polymer or polytetrafluoroethylene.

[0080] With the above configuration, the relative permittivity of the second region 120 can be reduced, and the characteristic impedance of the short stub 5 can be increased.

[0081] (4) Modified Example In the modified antenna 100 of Embodiment 1, not the entire short stub 5 but a part of the short stub 5 is placed in the second region 120 of the dielectric substrate 1, and the remaining part of the short stub 5 is placed in the first region 110 or the third region 130.

[0082] The modified antenna 100 of Embodiment 1 provides the same effects as the antenna 100 of Embodiment 1.

[0083] (Embodiment 2) The antenna 100A according to Embodiment 2 will be described with reference to Figure 8. With respect to the antenna 100A according to Embodiment 2, components that are the same as those of the antenna 100 according to Embodiment 1 (see Figures 1 to 7) are denoted by the same reference numerals and their description is omitted.

[0084] (1) The antenna 100A according to the second embodiment differs from the antenna 100 according to the first embodiment in that the distance L3 between the ground electrode 6 and the main surface 131 of the third region 130 in the thickness direction D1 of the dielectric substrate 1 is greater than or equal to the distance L20 between the ground electrode 6 and the main surface 20 of the radiating electrode 2.

[0085] In the antenna 100A according to Embodiment 2, the thickness of the third region 130 is greater than the thickness of the first region 110 of the dielectric substrate 1.

[0086] (2) Effects The antenna 100A according to Embodiment 2 has the same effects as the antenna 100 according to Embodiment 1.

[0087] Furthermore, in the antenna 100A according to Embodiment 2, the distance L3 between the ground electrode 6 and the main surface 131 of the third region 130 in the thickness direction D1 of the dielectric substrate 1 is greater than or equal to the distance L20 between the ground electrode 6 and the main surface 20 of the radiating electrode 2.

[0088] According to the above configuration, the thickness of the portion of the third region 130 of the dielectric substrate 1 between the open stub 7 and the main surface 131 increases, which reduces the characteristic impedance of the open stub 7 and makes it possible to further shorten the stub length of the open stub 7.

[0089] (3) Modified Example In the modified antenna 100A of Embodiment 2, the distance L3 between the ground electrode 6 and the main surface 131 of the third region 130 in the thickness direction D1 of the dielectric substrate 1 is the same as the distance L1 between the ground electrode 6 and the main surface 111 of the first region 110 in the thickness direction D1 of the dielectric substrate 1.

[0090] The modified antenna 100A of Embodiment 2 provides the same effects as the antenna 100A of Embodiment 2.

[0091] (Embodiment 3) The antenna 100B according to Embodiment 3 will be described with reference to Figures 9 and 10. With respect to the antenna 100B according to Embodiment 3, components that are the same as those of the antenna 100 according to Embodiment 1 (see Figures 1 to 7) are denoted by the same reference numerals and their description is omitted.

[0092] (1) The antenna 100B according to Embodiment 3 differs from the antenna 100 according to Embodiment 1 in that it comprises a plurality of short stubs 50 (two in the illustrated example) branching from the transmission line 3, and a plurality of second connecting conductor portions 40b (see Figure 10) corresponding one-to-one to the plurality of short stubs 50. Furthermore, the antenna 100B according to Embodiment 3 differs from the antenna 100 according to Embodiment 1 in that it comprises a plurality of open stubs 70 (two in the illustrated example) branching from the transmission line 3. The tip 701 of each of the plurality of open stubs 70 is open.

[0093] Multiple short stubs 50 include short stub 5. In other words, short stub 5 is one of the multiple short stubs 50. The materials of the multiple short stubs 50 are the same as each other. The materials of the multiple short stubs 50 include, for example, copper.

[0094] In this embodiment, the two short stubs 50 are arranged within the second region 120 of the dielectric substrate 1. The two short stubs 50 protrude from the transmission line 3 in opposite directions. More specifically, the two short stubs 50 protrude from the first transmission line 31 in opposite directions in the linewidth direction (direction parallel to the X-axis) of the first transmission line 31. The lengths of the two short stubs 50 are the same. The phrase "the lengths of the multiple short stubs 50 are the same" is not limited to the case where the length of any one of the multiple short stubs 50 is taken as a reference value and the lengths of the other short stubs 50 are the same as the reference value, but also includes the case where the lengths are 90% or more and 110% or less of the reference value. The multiple short stubs 50 are included in the conductive layer 41 (see Figure 10).

[0095] Each of the multiple second connecting conductor sections 40b connects the tip 501 of the corresponding short stub 50 from among the multiple short stubs 50 to the ground electrode 6. The multiple second connecting conductor sections 40b include a second connecting conductor section 4b. In other words, the second connecting conductor section 4b is one of the multiple second connecting conductor sections 40b.

[0096] Multiple open stubs 70 include open stub 7. The materials of the multiple open stubs 70 are the same as each other. The materials of the multiple open stubs 70 include, for example, copper.

[0097] In this embodiment, the two open stubs 70 are arranged within a third region 130 of the dielectric substrate 1. In this embodiment, the two open stubs 70 protrude from the transmission line 3 in opposite directions along the X-axis. More specifically, the two open stubs 70 protrude from the second transmission line 32 in opposite directions along the linewidth direction of the second transmission line 32. In this embodiment, the lengths of the two open stubs 70 are the same. The phrase "the lengths of the multiple open stubs 70 are the same" is not limited to the case where the length of any one of the multiple open stubs 70 is taken as a reference value and the lengths of the other open stubs 70 are the same as the reference value, but also includes the case where the lengths are 90% or more and 110% or less of the reference value. The multiple open stubs 70 are included in the conductive layer 40 (see Figure 10).

[0098] (2) Effects The antenna 100B according to Embodiment 3 has the same effects as the antenna 100 according to Embodiment 1.

[0099] Furthermore, the antenna 100B according to Embodiment 3 further comprises a plurality of short stubs 50 branching from the transmission line 3. Each of the plurality of short stubs 50 is located in the second region 120. The plurality of short stubs 50 includes a short stub 5.

[0100] According to the above configuration, the stub length per stub can be shortened, and the self-resonant frequency of the short stub 50 can be shifted to a higher frequency side than the operating frequency band of the antenna 100B. "The length per stub can be shortened" means that the length of each of the multiple short stubs 50 can be shortened compared to the length of a single short stub 50.

[0101] Furthermore, the antenna 100B according to Embodiment 3 further comprises a plurality of open stubs 70 branching from the transmission line 3. Each of the plurality of open stubs 70 is located in the third region 130 of the dielectric substrate 1. The plurality of open stubs 70 includes an open stub 7.

[0102] According to the above configuration, the stub length per stub can be shortened, and the self-resonant frequency of the open stub 70 can be shifted to a higher frequency side than the operating frequency band of the antenna 100B. "The length per stub can be shortened" means that the length of each of the multiple open stubs 70 can be shortened compared to the length of the open stub 70 when there is only one open stub 70.

[0103] (3) Modified Example 1 of the Modified Example 3, the antenna 100B has a portion of each of the two short stubs 50, rather than the whole, located within the second region 120 of the dielectric substrate 1, with the remaining portion located in the first region 110 or the third region 130.

[0104] In the modified example 2 of Embodiment 3, the antenna 100B has a portion, not all, of each of the two open stubs 70 located within the third region 130 of the dielectric substrate 1, with the remaining portion located within the second region 120.

[0105] In the antenna 100B according to the modification 3 of Embodiment 3, the lengths of the multiple short stubs 50 are different from each other.

[0106] In the antenna 100B according to modification 4 of embodiment 3, the lengths of the multiple open stubs 70 are different from each other.

[0107] In the modified example 5 of Embodiment 3, the antenna 100B has one open stub 7 instead of multiple open stubs.

[0108] In the modified example 6 of Embodiment 3, the antenna 100B has one short stub 50 instead of multiple stubs.

[0109] (Embodiment 4) The antenna 100C according to Embodiment 4 will be described with reference to Figure 11. With respect to the antenna 100C according to Embodiment 4, components that are the same as those of the antenna 100 according to Embodiment 1 (see Figures 1 to 7) are denoted by the same reference numerals and their description is omitted.

[0110] (1) The antenna 100C according to the fourth embodiment differs from the antenna 100 according to the first embodiment in that the dielectric substrate 1 has an inclined surface 141, as shown in Figure 11. The inclined surface 141 connects the main surface 121 of the second region 120 and the main surface 131 of the third region 130. The inclined surface 141 is inclined with respect to the main surface 121 of the second region 120 and the main surface 131 of the third region 130.

[0111] In this embodiment, the dielectric substrate 1 has a fourth region 140 between the second region 120 and the third region 130 in which the thickness of the dielectric substrate 1 gradually changes, and the fourth region 140 has an inclined surface 141.

[0112] Furthermore, in the antenna 100C according to Embodiment 4, the dielectric substrate 1 further has a second inclined surface 142 that is different from the inclined surface 141 (first inclined surface 141). The second inclined surface 142 is located between the main surface 121 of the second region 120 and the main surface 111 of the first region 110, and is connected to the main surface 121 of the second region 120. The second inclined surface 142 is inclined with respect to the main surface 121 of the second region 120 and the main surface 111 of the first region 110.

[0113] (2) Effects The antenna 100C according to Embodiment 4 has the same effects as the antenna 100 according to Embodiment 1.

[0114] Furthermore, in the antenna 100C according to Embodiment 4, the dielectric substrate 1 has an inclined surface 141. The inclined surface 141 connects the main surface 121 of the second region 120 and the main surface 131 of the third region 130 of the dielectric substrate 1, and is inclined with respect to the main surface 121 of the second region 120 and the main surface 131 of the third region 130.

[0115] According to the above configuration, abrupt changes in the effective relative permittivity around the transmission line 3 between the second region 120 and the third region 130 can be reduced, and reflections due to discontinuities in the characteristic impedance of the transmission line 3 can be reduced.

[0116] Furthermore, in the antenna 100C according to Embodiment 4, the dielectric substrate 1 further has a second inclined surface 142 that is different from the first inclined surface 141, which is the inclined surface 141. The second inclined surface 142 is located between the main surface 121 of the second region 120 and the main surface 111 of the first region 110, and is connected to the main surface 121 of the second region 120. The second inclined surface 142 is inclined with respect to the main surface 121 of the second region 120 and the main surface 111 of the first region 110.

[0117] According to the above configuration, abrupt changes in the effective relative permittivity around the transmission line 3 between the first region 110 and the second region 120 can be reduced, and reflections due to discontinuities in the characteristic impedance of the transmission line 3 can be reduced.

[0118] (3) Modified Example In the antenna 100C according to Modified Example 1 of Embodiment 4, the short stub 5 is arranged across the second region 120, the fourth region 140, and the third region 130. In the antenna 100C according to Modified Example 1 of Embodiment 4, reflection due to discontinuities in the characteristic impedance of the transmission line 3 and the short stub 5 can be reduced.

[0119] In the antenna 100C according to the modification 2 of Embodiment 4, the open stub 7 is arranged across the second region 120, the fourth region 140, and the third region 130. In the antenna 100C according to the modification 2 of Embodiment 4, reflections due to discontinuities in the characteristic impedance of the transmission line 3 and the open stub 7 can be reduced.

[0120] (Embodiment 5) The antenna 100D according to Embodiment 5 will be described with reference to Figure 12. With respect to the antenna 100D according to Embodiment 5, components that are the same as those of the antenna 100 according to Embodiment 1 (see Figures 1 to 7) are denoted by the same reference numerals and their description is omitted.

[0121] (1) The antenna 100D according to the 5th embodiment further comprises a resin portion 65 that covers the main surface 121 of the second region 120 and a part of the main surface 131 of the third region 130 of the dielectric substrate 1. The resin portion 65 is provided as a reinforcing portion that reinforces the second region 120 of the dielectric substrate 1. The relative permittivity of the resin portion 65 is greater than the relative permittivity of the dielectric substrate 1.

[0122] The resin portion 65 contains resin. The resin of the resin portion 65 is different from the dielectric material of the dielectric substrate 1. Examples of resins include epoxy resin, polyurethane resin, silicone resin, polyester resin, etc. The resin portion 65 contains a filler in addition to the resin to lower the coefficient of linear expansion of the resin portion 65. An example of the filler material is alumina. As described above, the relative permittivity of the resin portion 65 is greater than that of the dielectric substrate 1. If the resin portion 65 contains a resin with a relative permittivity higher than that of the dielectric substrate 1, it may or may not contain a filler.

[0123] (2) Effects The antenna 100D according to Embodiment 5 has the same effects as the antenna 100 according to Embodiment 1.

[0124] Furthermore, the antenna 100D according to Embodiment 5 further includes a resin portion 65 that covers the main surface 121 of the second region 120 and a part of the main surface 131 of the third region 130 of the dielectric substrate 1. The relative permittivity of the resin portion 65 is greater than that of the dielectric substrate 1.

[0125] According to the above configuration, the effective relative permittivity around the open stub 7 increases, making it possible to further shorten the stub length of the open stub 7.

[0126] (Embodiment 6) The antenna 100E according to Embodiment 6 will be described with reference to Figure 13. With respect to the antenna 100E according to Embodiment 6, components that are the same as those of the antenna 100 according to Embodiment 1 (see Figures 1 to 7) are denoted by the same reference numerals and their description is omitted.

[0127] (1) The antenna 100E according to the 6th embodiment further comprises a protective layer 66 that covers a part of the main surface 121 of the second region 120 and the main surface 131 of the third region 130 of the dielectric substrate 1. The protective layer 66 has the function of reinforcing the second region 120 of the dielectric substrate 1. The Young's modulus of the protective layer 66 is smaller than the Young's modulus of the dielectric substrate 1. The relative permittivity of the protective layer 66 is larger than the relative permittivity of air. Note that the protective layer 66 only needs to cover at least a part of the main surface 121 of the second region 120 and at least a part of the main surface 131 of the third region 130 of the dielectric substrate 1.

[0128] The protective layer 66 includes, for example, a polyimide film and an adhesive layer. The material of the adhesive layer includes, for example, an acrylic resin, a silicone resin, an epoxy resin, or a urethane resin.

[0129] (2) Effects The antenna 100E according to Embodiment 6 has the same effects as the antenna 100 according to Embodiment 1.

[0130] Furthermore, the antenna 100E according to Embodiment 6 further includes a protective layer 66 that covers at least a portion of the main surface 121 of the second region 120 and at least a portion of the main surface 131 of the third region 130 of the dielectric substrate 1. The Young's modulus of the protective layer 66 is smaller than that of the dielectric substrate 1.

[0131] According to the above configuration, the effective relative permittivity around the open stub 7 increases, making it possible to further shorten the stub length of the open stub 7.

[0132] (Embodiment 7) The antenna 100F according to Embodiment 7 will be described with reference to Figure 14. With respect to the antenna 100F according to Embodiment 7, components that are the same as those of the antenna 100 according to Embodiment 1 (see Figures 1 to 7) are denoted by the same reference numerals and their description is omitted.

[0133] (1) The antenna 100F according to the 7th embodiment differs from the antenna 100 according to the 1st embodiment in that at least a part (in this embodiment, all) of the short stub 5 is arranged on the main surface 121 of the second region 120 of the dielectric substrate 1.

[0134] In this embodiment, in the thickness direction D1 of the dielectric substrate 1, dielectric layers 12 to 19 are not present on the main surface of the short stub 5 opposite to the ground electrode 6 side. Dielectric layers 9 to 11 are present between the short stub 5 and the ground electrode 6. In this embodiment, the main surface of the short stub 5 is in contact with air.

[0135] (2) Effect The antenna 100F according to Embodiment 7 can shorten the stub length, similar to the antenna 100 according to Embodiment 1.

[0136] Furthermore, in the antenna 100F according to Embodiment 7, the short stub 5 is positioned on the main surface 121 of the second region 120 of the dielectric substrate 1.

[0137] According to the above configuration, the distance between the main surface 121 of the second region 120 in the thickness direction D1 of the dielectric substrate 1 and the short stub 5 can be made zero, and the effective relative permittivity around the short stub 5 can be further reduced, so the characteristic impedance of the short stub 5 can be further increased and the stub length of the short stub 5 can be further shortened.

[0138] (3) Modified Example 7: In the modified antenna 100F, not the entirety of the short stub 5, but a part of the short stub 5 is placed on the main surface 121 of the second region 120 of the dielectric substrate 1, and the remaining part of the short stub 5 is placed in the third region 130 of the dielectric substrate 1.

[0139] The modified antenna 100F of Embodiment 7, like the antenna 100 of Embodiment 1, makes it possible to shorten the stub length of the short stub 5.

[0140] (Modifications) Embodiments 1 to 7 described above are merely one of many embodiments of the present invention. Embodiments 1 to 7 described above can be modified in various ways depending on the design, etc., as long as the objective of the present invention is achieved, and may be combined as appropriate.

[0141] Each of the dielectric layers 9 to 19 may be made of, for example, polyimide (PI) or modified polyimide (Modified-PI). In this case, each of the first connecting conductor portion 4a, the second connecting conductor portion 4b, the third connecting conductor portion 4c, and the fourth connecting conductor portion 4d may be made of through-hole plating. The material for the through-hole plating is, for example, copper. The dielectric substrate 1 may also have an adhesive layer interposed between two adjacent dielectric layers in the thickness direction D1 of the dielectric substrate 1. That is, "multiple dielectric layers are laminated" is not limited to a configuration in which there is no adhesive layer interposed between two adjacent dielectric layers in the thickness direction D1 of the dielectric substrate 1, but also includes a configuration in which there is an adhesive layer interposed between two adjacent dielectric layers in the thickness direction D1 of the dielectric substrate 1. The adhesive layer includes a thermosetting resin. The thermosetting resin includes, for example, an epoxy resin or an acrylic resin.

[0142] Furthermore, antennas 100, 100A to 100F may further include at least one of a first protective film disposed on the first main surface 101 of the dielectric substrate 1 and covering at least a portion of the radiating electrode 2, and a second protective film disposed on the second main surface 102 of the dielectric substrate 1 and covering a portion of the ground electrode 6 and the feeding electrode 8, respectively. Each of the first and second protective films includes, for example, a polyimide film and an adhesive layer. The material of the adhesive layer includes, for example, an acrylic resin, a silicone resin, an epoxy resin, or a urethane resin. Each of the first and second protective films is not limited to a configuration including a polyimide film and an adhesive layer, but may also be a protective film formed using, for example, spin coating technology and photolithography technology.

[0143] Furthermore, each of the multiple conductive layers 39 to 49 is not limited to metal foil, but may also be a metal layer formed using thin-film formation techniques such as sputtering or vapor deposition. In this case, patterning may be performed using, for example, lithography and etching techniques, laser processing techniques, or the lift-off method.

[0144] The material of the dielectric substrate 1 is not limited to resin, but may also be, for example, ceramic. The ceramic may be, for example, LTCC (Low Temperature Co-fired Ceramics). The ceramic may also be, for example, HTCC (High Temperature Co-fired Ceramics).

[0145] Furthermore, the open stub 7 is not limited to a stub protruding from the second transmission line 32, but may also be a stub protruding from the first transmission line 31. In this case, the transmission line 3 only needs to have at least the first transmission line 31 and may not have the second transmission line 32. Also, antennas 100, 100A to 100F may be configured without the open stub 7.

[0146] In embodiments 1 to 6, the short stub 5 may be arranged on the main surface 121 of the second region 120 of the dielectric substrate 1, similar to embodiment 7.

[0147] 1 Dielectric substrate 101 First main surface 102 Second main surface 110 First region 111 Main surface 120 Second region 121 Main surface 130 Third region 131 Main surface 2 Radiating electrode 20 Main surface 3 Transmission line 31 First transmission line 32 Second transmission line 4a First connecting conductor part 4b Second connecting conductor part 40b Second connecting conductor part 4c Third connecting conductor part 4d Fourth connecting conductor part 5 Short stub 51 Tip 50 Short stub 501 Tip 6 Ground electrode 7 Open stub 71 Tip 70 Open stub 701 Tip 8 Power supply electrode 9-19 Dielectric layer 39-49 Conductive layer 65 Resin part 66 Protective layer 100, 100A, 100B, 100C, 100D, 100E, 100F Antenna 110 First region 111 Main surface 120 Second region 121 Main surface 130 Third region 131 Main surface 140 Fourth region 141 Inclined surface (First inclined surface) 142 Second inclined surface 401 Connecting electrodes L1 Distance L2 Distance L3 Distance L20 Distance L31 Distance L32 Distance L56 Distance L76 Distance V9-V19 Connecting conductors

Claims

1. A dielectric substrate having a first main surface and a second main surface; a radiating electrode disposed on the first main surface of the dielectric substrate; a transmission line disposed on the dielectric substrate and spaced apart from the radiating electrode in the thickness direction of the dielectric substrate; a first connecting conductor portion disposed on the dielectric substrate and connecting the radiating electrode and the transmission line; a short stub disposed on the dielectric substrate and branching off from the transmission line; a ground electrode disposed on the second main surface of the dielectric substrate and facing the radiating electrode, the transmission line and the short stub in the thickness direction of the dielectric substrate; and a second connecting conductor portion disposed on the dielectric substrate and connecting the tip of the short stub and the ground electrode, wherein the dielectric substrate has a first region on which the radiating electrode is disposed; and a second region different from the first region on which at least a part of the short stub is disposed, and the distance between the main surface of the second region of the dielectric substrate and the ground electrode in the thickness direction of the dielectric substrate is shorter than the distance between the radiating electrode and the ground electrode in the thickness direction of the dielectric substrate. Antenna.

2. The antenna according to claim 1, wherein at least a portion of the short stub is located within the second region of the dielectric substrate.

3. The antenna according to claim 1, wherein at least a portion of the short stub is arranged on the main surface of the second region of the dielectric substrate.

4. The antenna according to any one of claims 1 to 3, further comprising a plurality of short stubs branching from the transmission line, wherein at least a portion of each of the plurality of short stubs is located in the second region, and the plurality of short stubs include the short stubs.

5. The antenna according to any one of claims 1 to 4, further comprising an open stub disposed on the dielectric substrate and branching off from the transmission line, wherein the dielectric substrate further has a third region, different from the first and second regions, on which at least a portion of the open stub is disposed, the ground electrode faces the radiating electrode, the transmission line, the short stub, and the open stub in the thickness direction of the dielectric substrate, and the distance between the main surface of the third region of the dielectric substrate and the ground electrode in the thickness direction of the dielectric substrate is longer than the distance between the main surface of the second region of the dielectric substrate and the ground electrode in the thickness direction of the dielectric substrate.

6. The antenna according to claim 5, wherein, in the thickness direction of the dielectric substrate, the distance between the short stub and the ground electrode is longer than the distance between the open stub and the ground electrode.

7. The antenna according to claim 5 or 6, wherein, in the thickness direction of the dielectric substrate, the distance between the ground electrode and the main surface of the third region is greater than or equal to the distance between the ground electrode and the main surface of the radiating electrode.

8. The antenna according to any one of claims 5 to 7, further comprising a plurality of open stubs branching from the transmission line, wherein at least a portion of each of the plurality of open stubs is located in the third region, and the plurality of open stubs include the open stubs.

9. The antenna according to claim 5 or 6, wherein the dielectric substrate connects the main surface of the second region and the main surface of the third region, and has an inclined surface that is inclined with respect to the main surface of the second region and the main surface of the third region.

10. The antenna according to any one of claims 5 to 9, further comprising a resin portion covering the main surface of the second region and a part of the main surface of the third region of the dielectric substrate, wherein the relative permittivity of the resin portion is greater than the relative permittivity of the dielectric substrate.

11. The antenna according to claim 5 or 6, further comprising a protective layer covering at least a portion of the main surface of the second region and at least a portion of the main surface of the third region of the dielectric substrate, wherein the Young's modulus of the protective layer is less than that of the dielectric substrate.

12. The antenna according to any one of claims 1 to 10, wherein the dielectric substrate has a plurality of dielectric layers, and the plurality of dielectric layers are stacked.

13. The antenna according to claim 12, further comprising a plurality of conductive layers, wherein the plurality of dielectric layers and the plurality of conductive layers are laminated, and the plurality of conductive layers include a first conductive layer including the radiating electrode, a second conductive layer including the ground electrode, and a third conductive layer including the short stub.

14. The antenna according to claim 12 or 13, wherein the material of each of the plurality of dielectric layers includes a thermoplastic resin.

15. The antenna according to claim 14, wherein the thermoplastic resin comprises a liquid crystal polymer or polytetrafluoroethylene.

Images