Antenna module and communication device

Abstract

The present invention improves cross-polarization characteristics. The present invention comprises a dielectric substrate, a plurality of radiation elements, and a ground electrode. The dielectric substrate includes a first substrate, a second substrate having a normal direction different from that of the first substrate, and a bent portion connecting the first substrate and the second substrate. The first substrate has: a protrusion comprising a section protruding in a first direction and a section positioned on the side of the protruding section in a direction opposite from the first direction; and a cutout portion which is a section other than the protrusion and which is positioned in a second direction of the protrusion intersecting the first direction, along the first substrate. The bent portion is connected to the first substrate at the cutout portion. The ground electrode has a first ground electrode disposed facing the radiation elements provided to the protrusion. The shape of the first ground electrode is a straight line extending in the second direction and has line symmetry when a straight line passing through the geometric center of the first ground electrode is taken as the axis of symmetry.

Description

Antenna module and communication device

[0001] The present invention relates to an antenna module and a communication device.

[0002] Patent document 1 discloses an antenna module comprising a dielectric substrate including two flat portions whose normal directions are different from each other, a bent portion connecting the two flat portions, and a radiating element arranged on the dielectric substrate.

[0003] Japanese Patent Application Laid-Open No. 2021-69109

[0004] In the antenna module disclosed in Patent Document 1, a ground electrode is disposed on the surface or inner layer of the flat portion facing the mounting substrate. However, the structure of the antenna module described in Patent Document 1 requires a protruding shape to be provided on the dielectric substrate in order to connect the bent portion, which results in an asymmetrical shape of the ground electrode, leaving room for improvement in cross polarization characteristics.

[0005] The present invention has been made in view of the above, and provides an antenna module and a communication device that improve cross-polarization characteristics.

[0006] an antenna module according to one aspect of the present invention comprising a dielectric substrate, a plurality of radiating elements arranged on the dielectric substrate, and a ground electrode arranged on the dielectric substrate opposite the radiating elements; the dielectric substrate including a first substrate on which the radiating elements and the ground electrode are provided, a second substrate having a normal direction different from that of the first substrate, and a bent portion connecting the first substrate and the second substrate; the first substrate having a protruding portion including a portion that protrudes along the first substrate in a first direction toward the second substrate and a portion of the protruding portion in a direction opposite to the first direction, and a notched portion of the protruding portion in a second direction along the first substrate that intersects with the first direction, the bent portion being connected to the first substrate at the notched portion; the ground electrode having a first ground electrode arranged opposite the radiating elements provided on the protruding portion, the shape of the first ground electrode being a straight line extending in the second direction and passing through the geometric center of the first ground electrode being an axis of symmetry;

[0007] According to the present invention, it is possible to provide an antenna module and a communication device that improve cross-polarization characteristics.

[0008] FIG. 1 is a diagram illustrating an example of a block diagram of a communication device to which an antenna module according to a first embodiment is applied. FIG. 2 is a perspective view of the antenna module according to the first embodiment. FIG. 3 is a side view of the antenna module according to FIG. 2 mounted on a mounting substrate. FIG. 4 is a cross-sectional view of the antenna module incorporated inside the housing of the communication device. FIG. 5 is a diagram illustrating the path of a feed wiring that transmits a high-frequency signal to a feed element on a first substrate. FIG. 6 is a plan view illustrating the shape of a ground electrode according to the first embodiment. FIG. 7 is a plan view illustrating a ground electrode provided on the first substrate of an antenna device of an antenna module according to a second embodiment. FIG. 8 is a plan view illustrating a ground electrode provided on the first substrate of an antenna device of an antenna module according to a third embodiment. FIG. 9 is a plan view illustrating a ground electrode provided on the first substrate of an antenna device of an antenna module according to a fourth embodiment. FIG. 10 is a plan view illustrating a ground electrode provided on the first substrate of an antenna device of an antenna module according to a comparative example. FIG. 11 is a diagram illustrating a simulation result of a radiation pattern of a horizontally polarized wave component according to a comparative example. FIG. 12 is a diagram illustrating a simulation result of a radiation pattern of a horizontally polarized wave component according to an example. Fig. 13 is a diagram showing a simulation result of the radiation pattern of the horizontally polarized component according to the comparative example. Fig. 14 is a diagram showing a simulation result of the radiation pattern of the horizontally polarized component according to the example. Fig. 15 is a diagram showing a simulation result of the surface current distribution of the ground electrode of the antenna device of the antenna module according to the comparative example. Fig. 16 is a diagram showing a simulation result of the surface current distribution of the ground electrode of the antenna device of the antenna module according to the example. Fig. 17 is a schematic plan view illustrating surface current vectors in the ground electrode of the comparative example. Fig. 18 is a schematic plan view illustrating surface current vectors in the ground electrode of the example.

[0009] The following describes embodiments of the present invention. However, the present invention is not limited to these embodiments. Each embodiment is an example, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments is possible.

[0010] [First Embodiment] (Communication Device) Fig. 1 is an example block diagram of a communication device to which an antenna module according to a first embodiment is applied. The communication device 10 is, for example, a mobile terminal such as a mobile phone, smartphone, or tablet, or a personal computer with a communication function. An example of the frequency band of radio waves used in the antenna module 100 according to the first embodiment is millimeter-wave radio waves with center frequencies of, for example, 28 GHz, 39 GHz, and 60 GHz, but radio waves in other frequency bands are also applicable.

[0011] 1 , the communication device 10 includes an antenna module 100 and a BBIC 200 that constitutes a baseband signal processing circuit. The antenna module 100 includes an RFIC 110, which is an example of a power supply circuit, and an antenna device 120. The communication device 10 upconverts a signal transmitted from the BBIC 200 to the antenna module 100 into a high-frequency signal and radiates the signal from the antenna device 120, and downconverts the high-frequency signal received by the antenna device 120 and processes the signal in the BBIC 200.

[0012] The antenna device 120 includes a feed element 121. Here, the feed element 121 is an example of a "radiating element." For ease of explanation, FIG. 1 shows only the configurations corresponding to four of the multiple feed elements 121 of the antenna device 120, and omits the configurations corresponding to the other feed elements 121 having similar configurations. While FIG. 1 illustrates an example in which the antenna device 120 is formed with multiple feed elements 121 arranged in a two-dimensional array, the number of feed elements 121 is not necessarily multiple; the antenna device 120 may be formed with a single feed element 121. Alternatively, the antenna device 120 may be formed with a one-dimensional array in which multiple feed elements 121 are arranged in a row. In the first embodiment, the feed element 121 is a patch antenna having a rectangular flat plate shape.

[0013] The RFIC 110 includes switches 111A to 111D, 113A to 113D, and 117, power amplifiers 112AT to 112DT, low-noise amplifiers 112AR to 112DR, attenuators 114A to 114D, phase shifters 115A to 115D, a signal combiner / demultiplexer 116, a mixer 118, and an amplifier circuit 119.

[0014] When transmitting a high frequency signal, the switches 111A to 111D and 113A to 113D are switched to the side of the power amplifiers 112AT to 112DT, and the switch 117 is connected to the transmitting amplifier of the amplifier circuit 119. When receiving a high frequency signal, the switches 111A to 111D and 113A to 113D are switched to the side of the low noise amplifiers 112AR to 112DR, and the switch 117 is connected to the receiving amplifier of the amplifier circuit 119.

[0015] The signal transmitted from BBIC 200 is amplified by amplifier circuit 119 and up-converted by mixer 118. The up-converted high-frequency transmission signal is split into four by signal combiner / splitter 116, passes through four signal paths, and is fed to different feed elements 121. At this time, the phase shift of phase shifters 115A to 115D arranged on each signal path is individually adjusted, thereby adjusting the directivity of antenna device 120.

[0016] The received signals, which are high-frequency signals received by each of the feed elements 121, pass through four different signal paths and are combined by the signal combiner / demultiplexer 116. The combined received signal is down-converted by the mixer 118, amplified by the amplifier circuit 119, and transmitted to the BBIC 200.

[0017] The RFIC 110 may be formed as a single-chip integrated circuit component including the above circuit configuration, or the devices (switches, power amplifiers, low-noise amplifiers, attenuators, and phase shifters) corresponding to each of the feed elements 121 in the RFIC 110 may be formed as single-chip integrated circuit components for each of the feed elements 121.

[0018] (Antenna Module) Next, the antenna module 100 according to the first embodiment will be described in detail with reference to Fig. 2 and Fig. 3. Fig. 2 is a perspective view of the antenna module according to the first embodiment. Fig. 3 is a side view of the antenna module according to Fig. 2 mounted on a mounting board.

[0019] 2 and 3 , the antenna device 120 of the antenna module 100 includes a feed element 121, an RFIC 110, a dielectric substrate 105, feed lines 171 and 172, a ground electrode 180, a ground electrode 183, and a bent ground electrode 184. The dielectric substrate 105 includes a first substrate 131, a second substrate 132, and a bent portion 135.

[0020] The overall shape of the antenna device 120 will now be described.

[0021] The normal direction of the first substrate 131 and the normal direction of the second substrate 132 are different directions. In the present disclosure, the normal direction of the first substrate 131 refers to the thickness direction of the first substrate 131. Furthermore, the normal direction of the second substrate 132 refers to the thickness direction of the second substrate 132. The thickness direction of the first substrate 131 is the stacking direction of the first substrate 131, the ground electrode 180, and the feed element 121. The thickness direction of the second substrate 132 is the stacking direction of the second substrate 132, the ground electrode 183, and the feed element 121. The first substrate 131 and the second substrate 132 are connected by a bent portion 135. In other words, the antenna device 120 is a plate-like device bent by the bent portion 135. The first substrate 131, the second substrate 132, and the bent portion 135 are formed by partially processing and bending the dielectric substrate 105. In the example of Figures 2 and 3, the bent portion 135 extends from the first substrate 131 in a direction intersecting the thickness direction of the first substrate 131, and then bends in the thickness direction of the first substrate 131 to be connected to the second substrate 132.

[0022] In the following description, the thickness direction of the first substrate 131 is referred to as the X direction, the direction perpendicular to the X direction and in which the bent portion 135 extends from the first substrate 131 is referred to as the Z direction, and the direction perpendicular to the X and Z directions is referred to as the Y direction. Furthermore, a view along the X direction will be referred to as a front view, and a view along the Z direction will be referred to as a plan view.

[0023] 2, the thickness direction of the second substrate 132 is the Z direction. That is, the antenna device 120 has an L-shape when viewed in the Y direction. This shape makes it possible to reduce the area that the antenna device 120 occupies on the main surface of the mounting substrate 20, thereby making it possible to provide a miniaturized antenna module that can be placed in a limited space within a communication device.

[0024] In the following description, the direction from the inside to the outside of the L-shape, which is the shape of the antenna device 120, may be referred to as the X1 direction, and the direction from the outside to the inside of the L-shape may be referred to as the X2 direction. Furthermore, within the Z direction, the direction from the inside to the outside of the L-shape may be referred to as the Z1 direction, and the direction from the outside to the inside of the L-shape may be referred to as the Z2 direction. Here, the Z1 direction is the direction along the first substrate 131 toward the second substrate 132 and is an example of a "first direction." Furthermore, the Z2 direction is an example of a "direction opposite to the first direction." Furthermore, within the Y direction, one direction may be referred to as the Y1 direction, and the other direction may be referred to as the Y2 direction. In the following description, when simply referring to the X direction, Y direction, and Z direction, these will be described as referring to at least one of the X1 direction and the X2 direction, at least one of the Y1 direction and the Y2 direction, and at least one of the Z1 direction and the Z2 direction, respectively. Here, the Y direction is a direction along the first substrate 131 that intersects with the first direction and is an example of a "second direction."

[0025] Each component of the antenna device 120 will be described below.

[0026] The dielectric substrate 105 is, for example, a low temperature co-fired ceramics (LTCC) multilayer substrate, a multilayer resin substrate formed by laminating multiple resin layers made of resin such as epoxy or polyimide, a multilayer resin substrate formed by laminating multiple resin layers made of liquid crystal polymer (LCP) having a lower dielectric constant, a multilayer resin substrate formed by laminating multiple resin layers made of fluorine-based resin, or a ceramic multilayer substrate other than LTCC. Note that the dielectric substrate 105 does not necessarily have a multilayer structure and may be a single layer.

[0027] (First Substrate) The first substrate 131 has a thickness in the X direction, a first main surface 131a on the X1 direction side, and a second main surface 131b on the X2 direction side of the first substrate 131.

[0028] The first substrate 131 has a rectangular shape with a notched edge on the Z1 direction side when viewed from the front. The first substrate 131 has a protruding portion 133 and a notched portion 136. The protruding portion 133 is a portion of the first substrate 131 and consists of a portion 133a that protrudes from a notched side surface 134 along the first substrate 131 toward the second substrate 132 (the Z1 direction) and a portion 133b of the protruding portion located in the Z2 direction. The notched portion 136 is a portion of the first substrate 131 other than the protruding portion 133 and is a portion of the protruding portion 133 located in the Y direction. In the first embodiment, the notched portion 136 is a portion located in the Z2 direction relative to the notched side surface 134 to which the bent portion 135 is connected. In FIG. 2 , the portion 133a, the portion 133b, and the notched portion 136 are portions of the first substrate 131 separated by dashed lines. This shape allows the bent portion 135 to be connected to the notch 136 with sufficient strength, while ensuring sufficient space for providing the feed element 121 without increasing the length of the first substrate 131 in the Z direction, as described below. This allows for a compact antenna device 120. In the example shown in FIG. 2 , the first substrate 131 has two protrusions 133 and three notches 136. However, the number of protrusions 133 and the number of notches 136 are merely an example and are not limited to this. Furthermore, the notches 136 are provided between the two protrusions 133 in the Y direction and at both ends in the Y direction. However, the positions of the notches 136 relative to the protrusions 133 in the Y direction are not limited thereto. The notches 136 may be provided only between the protrusions 133 in the Y direction, or only at the ends of the protrusions 133 in the Y direction.

[0029] Here, of the side surfaces of the first substrate 131 on the Z direction side, the side surface at the notch 136 is the notch side surface 134. Also, of the side surfaces of the first substrate 131 on the Z1 direction side, the surfaces other than the notch side surface 134 are the side surfaces of the protrusion 133. In other words, the side surfaces of the protrusion 133 are surfaces on the Z1 direction side of the notch side surface 134.

[0030] (Second Substrate) The second substrate 132 has a thickness in the Z direction, a first main surface 132a on the Z1 direction side, and a second main surface 132b on the Z2 direction side of the second substrate 132. The shape of the second substrate 132 is rectangular in plan view. Here, it is preferable that the thickness of the second substrate 132 is the same as the thickness of the first substrate 131. This makes it possible to suppress a deterioration in the antenna characteristics of the feed element 121 of the first substrate 131 that accompanies a reduction in thickness.

[0031] The RFIC 110 is connected to the second main surface 132b of the second substrate 132. The RFIC 110 is mounted on the surface 21 of the mounting substrate 20 via bumps 140. The bumps 140 are made of solder, for example. Note that instead of mounting the RFIC 110 on the mounting substrate 20 using the bumps 140, the RFIC 110 may be mounted on the mounting substrate 20 using a multi-pole connector.

[0032] Here, the positional relationship between the second substrate 132 and the first substrate 131 will be described in detail. FIG. 4 is a cross-sectional view of the antenna module incorporated inside the housing of a communication device. The antenna module 100 is disposed so as to face the inner surfaces of two adjacent surfaces of the housing 30. In the example of FIG. 4 , the housing 30 is formed of a dielectric material such as resin or glass, and, for example, the feed element 121 is disposed so as to contact the housing 30. Note that if the feed element 121 is disposed in an internal layer, the first substrate 131 and the second substrate 132 are disposed so as to contact the housing 30. Furthermore, if the housing 30 is formed of a metal material, the housing 30 itself acts as a shield that blocks radio waves, so a dielectric material is provided on the portion of the housing 30 that faces the feed element 121.

[0033] In the first embodiment, when viewed from the front, the first substrate 131 overlaps at least a portion of the second substrate 132. In the example of FIG. 4 , the side of the protrusion 133 is located in the Z1 direction relative to the cutout side surface 134. The first substrate 131 is formed so that the side of the protrusion 133 of the first substrate 131 is located in the Z1 direction relative to the bent portion 135, causing the protrusion 133 of the first substrate 131 to protrude into an area AR1 located on an inner corner side of the housing 30. In the example of FIG. 4 , the side of the protrusion 133 and the first main surface 132a of the second substrate 132 are positioned in the same Z direction. This allows the bent portion 135 to be connected to the cutout portion 136 with sufficient strength, while ensuring sufficient space on the first substrate 131 for providing the feed element 121. This allows the overall Z-direction dimension of the antenna module to be reduced while maintaining the size of the feed element 121.

[0034] (Bent portion) The bent portion 135 has a bend and connects the first substrate 131 and the second substrate 132. The bent portion 135 is connected to the first substrate 131 at the notch portion 136. In the example of Fig. 2, the bent portion 135 extends from the X2 direction side of the notch side surface 134 of the first substrate 131, bending from the Z1 direction to the X2 direction, and is connected to the Z2 direction side of the second substrate 132.

[0035] (Feeding Elements) The feeding elements 121 are provided on each of the first substrate 131 and the second substrate 132. In the example of FIG. 2 , four feeding elements 121 are arranged on the first main surface 131 a of the first substrate 131 so as to be aligned in the Y direction, and four feeding elements 121 are arranged on the first main surface 132 a of the second substrate 132 so as to be aligned in the Y direction. Here, on the first substrate 131, the four feeding elements 121 are provided on the protrusion 133. In the example of FIG. 6 described below, in a front view, the geometric centers C of the four feeding elements 121 are aligned on a line SA extending in the Y direction and passing through the geometric center C1 of a first ground electrode 181 described below. Note that the number and arrangement of the feeding elements 121 are merely examples and are not limited thereto. For example, the feeding elements 121 may be arranged such that their geometric centers C are eccentric with respect to the line SA. Furthermore, the feeding element 121 may be disposed inside the first substrate 131 or the second substrate 132 .

[0036] The feed element 121 is provided on the protrusion 133. That is, the feed element 121 is not provided in the cutout 136 of the first substrate 131. This allows the Z-direction position of the feed element 121 to be located on the Z1-direction side of the Z-direction position of the cutout side surface 134, thereby reducing the Z-direction length of the first substrate and achieving a more compact antenna device 120. In the example of FIG. 2, two feed elements 121 are provided between each of the cutouts 136 in the Y-direction, but this is merely an example and the number of feed elements is not limited thereto. Also, in the example of FIG. 2, the feed element 121 has a feed point SP to which the feed wiring 171 is connected. Note that the location of the feed point SP is merely an example.

[0037] (Power feed wiring) The power feed wiring 171 is a wiring that transmits a high-frequency signal from the RFIC 110 to the power feed element 121 of the first substrate 131. The power feed wiring 171 runs from the RFIC 110 through the inside of the second substrate 132, the inside (or the surface) of the bent portion 135, and the inside of the first substrate 131, and is connected to the power feed element 121 provided on the first substrate 131.

[0038] 5 is a diagram illustrating the path of a feed wiring that transmits a high-frequency signal to a feed element on the first substrate. As shown in FIG. 5 , the feed wiring 171 runs from the RFIC 110 through the inside of the second substrate 132, passes through the bent portion 135, and reaches the first substrate 131. In the first substrate 131, the feed wiring 171 bends in the Y1 direction from the boundary between the second main surface 131b and the cutout side surface 134, where the bent portion 135 is connected to the first substrate 131, and is then connected to the feed element 121.

[0039] The power supply wiring 172 is a wiring that transmits a high-frequency signal from the RFIC 110 to the power supply element 121 on the second substrate 132 .

[0040] (Ground Electrode) The ground electrode 183 is disposed on the second main surface 132b or an inner layer of the second substrate 132. The ground electrode 183 is connected to a reference potential.

[0041] (Bent Ground Electrode) The bent ground electrode 184 is disposed on the surface or inner layer of the bent portion 135 on the mounting substrate 20 side. The bent ground electrode 184 is electrically connected to the ground electrode 183, and is thereby connected to the reference potential. This makes it possible to suppress radiation from the power supply wiring 171 of the bent portion 135.

[0042] (Ground Electrode) FIG. 6 is a plan view showing the shape of the ground electrode according to the first embodiment. The ground electrode 180 is provided on or inside the second main surface 131b of the first substrate 131. The ground electrode 180 is provided in a region that overlaps with at least a portion of the first substrate 131 when viewed from the front. In the example of FIG. 4, the ground electrode 180 is provided on a portion of the second main surface 131b of the first substrate 131. In the present disclosure, a ground electrode is an electrode that is not connected to a potential other than the reference potential. In other words, the ground electrode includes a so-called floating electrode that is not connected to a specific potential.

[0043] (First Ground Electrode) In the first embodiment, the ground electrode 180 includes a first ground electrode 181. The first ground electrode 181 is disposed opposite the power supply element 121. In other words, the first ground electrode 181 overlaps with the power supply element 121 in a front view. In the example of Fig. 6, the first ground electrode 181 is a so-called floating electrode that is not connected to a specific potential. In the example of Fig. 6, one first ground electrode 181 is provided on each of the two protrusions 133.

[0044] In the first embodiment, the first ground electrode 181 has an axisymmetric shape with respect to a straight line SA as an axis of symmetry when viewed from the front. The straight line SA is a line extending in the Y direction and passing through the geometric center C1 of the first ground electrode 181. In the first embodiment, the straight line SA is a line passing through multiple geometric centers C1 of the first ground electrode 181. In the example of FIG. 6 , the first ground electrode 181 is axisymmetric with respect to the straight line SA as the axis of symmetry. This can improve the cross polarization characteristics of the feed element 121.

[0045] 6, the ground electrode 180 further includes a second ground electrode 182. The second ground electrode 182 is a ground electrode that is provided spaced apart from the first ground electrode 181 in a front view.

[0046] At least a portion of the second ground electrode 182 is provided in the cutout portion 136 of the first substrate 131. In the example of Fig. 6, one second ground electrode 182 is provided in each of the three cutout portions 136 of the first substrate 131. This allows the second ground electrode 182 to improve the mechanical strength of the first substrate 131.

[0047] The second ground electrode 182 is electrically connected to the bent ground electrode 184 of the bent portion 135. This allows the second ground electrode 182 to suppress radiation from the power supply wiring 171. Note that, although all three second ground electrodes 182 are electrically connected to the bent ground electrode 184 of the bent portion 135 in the example of Fig. 5, at least one of the second ground electrodes 182 may be electrically connected to the bent ground electrode 184 of the bent portion 135.

[0048] In the first embodiment, the minimum distance w1 in the Y direction between the first ground electrode 181 and the second ground electrode 182 is equal to or greater than a quarter wavelength. This makes it possible to suppress coupling between the first ground electrode 181 and the second ground electrode 182. In the present disclosure, one wavelength refers to the wavelength of the electromagnetic wave emitted or received by the power supply element 121. That is, for example, a quarter wavelength refers to a length that is one-quarter of the wavelength of the electromagnetic wave emitted or received by the power supply element 121.

[0049] The second ground electrode 182 is not an essential component. That is, the ground electrode 180 does not necessarily have to be provided in the cutout portion 136.

[0050] As described above, the antenna module 100 according to the first embodiment includes the dielectric substrate 105, a plurality of radiating elements (feeding elements 121) arranged on the dielectric substrate 105, and the ground electrode 180 arranged on the dielectric substrate 105 opposite the radiating elements. The dielectric substrate 105 includes a first substrate 131 on which the radiating elements and the ground electrode 180 are provided, a second substrate 132 whose normal direction differs from that of the first substrate 131, and a bent portion 135 connecting the first substrate 131 and the second substrate 132. The first substrate 131 has a protruding portion 133 including a portion 133a protruding in a first direction (Z1 direction) along the first substrate toward the second substrate and a portion 133b of the protruding portion in the direction opposite to the first direction (Z2 direction), and a notch 136 in the portion other than the protruding portion 133, the protruding portion 133 in a second direction (at least one of the Y1 direction and the Y2 direction) intersecting the first direction along the first substrate 131. The bent portion 135 is connected to the first substrate 131 at the notch 136. The ground electrode 180 has a first ground electrode 181 disposed opposite the radiating element provided on the protruding portion 133. The shape of the first ground electrode 181 is a straight line extending in the second direction and is axisymmetric with respect to a line SA passing through the geometric center C1 of the first ground electrode 181 as an axis of symmetry.

[0051] By giving the first substrate 131 this shape, it is possible to connect the bent portion 135 to the cutout portion 136 with sufficient strength, while ensuring sufficient space for providing the radiating element on the first substrate 131, so it is possible to reduce the dimension of the entire antenna module 100 in the second direction while maintaining the size of the radiating element. By giving the first ground electrode 181 this shape, it is possible to improve the cross polarization characteristics of the radiating element even if the first substrate 131 has the above shape.

[0052] On the other hand, if the first ground electrode has the shape shown in Patent Document 1, that is, if it has the shape according to the comparative example described below, the first ground electrode (first ground electrode 181X according to Figure 10) has a second portion (second portion 181Xb according to Figure 10) that is asymmetric when viewed with the straight line SA as the axis of symmetry, and as a whole, the first ground electrode is not line-symmetric with respect to the axis of symmetry AZ, which may result in a deterioration in the cross-polarization characteristics of the radiating element.

[0053] In a preferred embodiment, the ground electrode 180 further includes a second ground electrode 182 that is provided in the cutout 136 and spaced apart from the first ground electrode 181. Therefore, the second ground electrode 182 is not symmetrical with respect to the straight line SA. However, since the second ground electrode 182 itself is spaced apart from the first ground electrode 181 in the third direction, the influence on the cross-polarization characteristics of the radiating element is suppressed. Furthermore, the second ground electrode 182 can improve the mechanical strength of the first substrate 131. Furthermore, in manufacturing the antenna module, the amount of ground electrode 180 that needs to be removed from the first substrate 131 can be reduced, thereby simplifying the process of removing the ground electrode 180, such as by etching.

[0054] In a preferred embodiment, the antenna further includes a bent ground electrode 184 that is provided on the surface of or inside the bent portion 135 and is connected to a reference potential. At least one second ground electrode 182 is connected to the bent ground electrode 184. This allows the bent ground electrode 184 to suppress radiation from the power supply wiring 171 inside the bent portion 135.

[0055] In a more preferable aspect, the minimum distance w1 between the first ground electrode and the second ground electrode when viewed along the normal direction of the first substrate is equal to or greater than a quarter wavelength, thereby suppressing coupling between the first ground electrode 181 and the second ground electrode 182.

[0056] As described above, the communication device 10 according to the first embodiment is equipped with the antenna module 100 according to the first embodiment, thereby providing a communication device that improves cross polarization characteristics.

[0057] Second Embodiment Fig. 7 is a plan view illustrating a ground electrode provided on a first substrate of an antenna device of an antenna module according to a second embodiment. As shown in Fig. 7, a ground electrode 180A according to the second embodiment does not have a second ground electrode 182. In the second embodiment, a first ground electrode 181A has a first portion 181a and a second portion 181b. In the example of Fig. 7, the shape of the first ground electrode 181A is rectangular with a rectangular cutout when viewed from the front.

[0058] The first portion 181a is a portion of the first ground electrode 181A that overlaps with the power supply element 121 in front view. Similar to the first ground electrode 181 in FIG. 6 , one first portion 181a is provided on each of the protruding portions 133 of the two first substrates 131.

[0059] The second portions 181b are provided in the cutouts 136. That is, the second portions 181b are portions of the first ground electrode 181A that are narrower in the Z direction than the first portions 181a. In the example of FIG. 7 , the second portions 181b are provided on each of the three cutouts 136 of the first substrate 131, one on each side in the Z1 direction. The Y direction sides of the second portions 181b are connected to the first portions 181a. More specifically, the second portions 181b are provided between the first portions 181a in the Y direction and on both sides in the Y direction. Note that the second portions 181b may be provided only between the first portions 181a in the Y direction, or only at the ends of the first portions 181a in the Y direction.

[0060] In the second embodiment, the first portion 181a is a straight line extending in the Y direction in a front view and has a shape that is line-symmetrical with respect to a line SA passing through the geometric center C2 of the first portion 181a. The second portion 181b is a straight line extending in the Y direction in a front view and has a shape that is line-symmetrical with respect to a line passing through the geometric center C3 of the second portion 181b. The geometric centers C3 of the multiple second portions 181b are located on the line SA. As a result, the first ground electrode 181A according to the second embodiment has a shape that is line-symmetrical with respect to the line SA passing through the geometric center C1A of the first ground electrode 181A in a front view. This improves the cross-polarization characteristics of the feed element 121. Furthermore, by forming the first ground electrode 181A to include the first portion 181a and the second portion 181b, the mechanical strength of the first substrate 131 can be improved.

[0061] In the second embodiment, the first ground electrode 181A is connected to a reference potential. In the example of Fig. 7, the second portion 181b, which will be described later, is electrically connected to the curved ground electrode 184. This connects the first ground electrode 181A, which is connected to the feed element 121, to the reference potential, allowing the feed element 121 to operate stably. Note that, although all three second portions 181b are electrically connected to the curved ground electrode 184 in the example of Fig. 7, at least one of the second portions 181b may be electrically connected to the curved ground electrode 184.

[0062] As described above, in the antenna module according to the second embodiment, the first ground electrode 181A has the first portion 181a disposed opposite the radiating element provided on the protrusion 133, and the second portion 181b provided in the cutout 136 and connected to the first portion 181a. By adopting this shape, the shape of the first ground electrode 181A can be made line-symmetrical with respect to the line SA that extends in the second direction and passes through the geometric center of the first ground electrode, and the mechanical strength of the first substrate 131 can be improved.

[0063] In a preferred embodiment, the antenna further includes a bent ground electrode 184 that is provided on the surface of or inside the bent portion 135 and is connected to a reference potential. At least one second portion 181b is connected to the bent ground electrode 184. This connects the first ground electrode 181A connected to the feed element 121 to the reference potential, allowing the feed element 121 to operate stably.

[0064] Third Embodiment FIG. 8 is a plan view illustrating a ground electrode provided on a first substrate of an antenna device of an antenna module according to a third embodiment. As shown in FIG. 8 , in a ground electrode 180B according to the third embodiment, the distance in the Y direction between a second ground electrode 182B and a first ground electrode 181 is uniform, i.e., not constant. In the example shown in FIG. 8 , the edge of the second ground electrode 182B provided on the first substrate 131 facing the first ground electrode 181 in the Y direction is sawtooth-shaped. In other words, the edge of the second ground electrode 182B facing the first ground electrode 181 in the Y direction has a shape that extends in the Z direction while oscillating between the Y1 and Y2 directions. This allows for suppression of coupling between the first ground electrode 181 and the second ground electrode 182B even when the distance in the Y direction between the first ground electrode 181 and the second ground electrode 182B is small.

[0065] In the second embodiment, the maximum distance w2 between the edge at the Y-direction end of the second ground electrode 182B and the edge at the Y-direction end of the first ground electrode 181 is preferably equal to or greater than one-sixth of the wavelength. This suppresses coupling between the first ground electrode 181 and the second ground electrode 182B, while allowing the second ground electrode 182B to improve the mechanical strength of the first substrate 131 and suppressing radiation from the power supply wiring 171. Furthermore, in manufacturing the antenna module, the amount of ground electrode removal between the first ground electrode 181 and the second ground electrode 182B in the Y-direction can be reduced, making it possible to simplify the ground electrode removal process, such as etching.

[0066] As described above, in the antenna module according to the third embodiment, when viewed along the normal direction of the first substrate, the distance between the second ground electrode 182B adjacent to the first ground electrode 181 and the first ground electrode 181 is not uniform. This makes it possible to suppress coupling between the first ground electrode 181 and the second ground electrode 182B even if the distance in the Y direction between the first ground electrode 181 and the second ground electrode 182B is reduced.

[0067] In a preferred embodiment, when viewed along the normal direction of the first substrate, the maximum distance between the first ground electrode 181 and the second ground electrode 182B adjacent to the first ground electrode 181 is equal to or greater than one-sixth of the wavelength. This suppresses coupling between the first ground electrode 181 and the second ground electrode 182B, while improving the mechanical strength of the first substrate 131 by the second ground electrode 182B and improving the stability of the reference potential. Furthermore, in manufacturing the antenna module, the amount of ground electrode removal between the first ground electrode 181 and the second ground electrode 182B in the Y direction can be suppressed, which simplifies the ground electrode removal process, such as etching.

[0068] [Fourth Embodiment] FIG. 9 is a plan view illustrating a ground electrode provided on a first substrate of an antenna device of an antenna module according to a fourth embodiment. As shown in FIG. 9 , in a ground electrode 180C according to the fourth embodiment, multiple second ground electrodes 182C are provided in a region of the cutout 136 of the first substrate 131 in the Z2 direction, spaced apart from one another in the Y direction. The multiple second ground electrodes 182C are adjacent to one another in the Y direction. Here, "spaced ground electrodes adjacent to one another in the Y direction" means that no other spaced ground electrodes are provided between the spaced ground electrodes in the Y direction. In the example of FIG. 9 , multiple strip-shaped second ground electrodes 182C extending in the Z direction are arranged side by side in the Y direction in a region of the cutout 136 of the first substrate 131 in the Z2 direction. This improves the mechanical strength of the first substrate 131, and the second ground electrodes 182B suppress radiation from the power supply wiring 171.

[0069] In the fourth embodiment, at least one second ground electrode 182C is not adjacent to the first ground electrode 181 in the Y direction and is connected to the bent ground electrode 184. In the example of FIG. 9 , among the multiple second ground electrodes 182C, the second ground electrode 182C adjacent to the first ground electrode 181 in the Y direction, for example, the second ground electrode 182C1, is a so-called floating electrode that is not connected to a specific potential. Furthermore, another second ground electrode 182C adjacent to the second ground electrode 182C adjacent to the first ground electrode 181 in the Y direction, for example, the second ground electrode 182C2, is also a so-called floating electrode that is not connected to a specific potential. Furthermore, another second ground electrode 182C that is not adjacent to the first ground electrode 181 or the second ground electrode 182C adjacent to the first ground electrode 181 in the Y direction, for example, the second ground electrode 182C3, is connected to the reference potential by the bent ground electrode 184. This suppresses coupling between the first ground electrode 181 and the second ground electrode 182C.

[0070] As described above, in the antenna module according to the fourth embodiment, a plurality of second ground electrodes 182C are provided in one of the cutout portions 136 of the first substrate 131. At least one second ground electrode 182C (second ground electrode 182C3) is adjacent to another second ground electrode 182C. This can improve the mechanical strength of the first substrate 131 and the stability of the reference potential.

[0071] In a preferred embodiment, the bent portion 135 further includes a bent ground electrode 184 that is provided on the surface or inside the bent portion 135 and connected to a reference potential. At least one second ground electrode 182C (second ground electrode 182C3) is connected to the bent ground electrode 184. The at least one second ground electrode 182C (second ground electrode 182C3) is not adjacent to the first ground electrode 181. This makes it possible to suppress coupling between the first ground electrode 181 and the second ground electrode 182C.

[0072] [Examples] Examples will be described below, but the present invention is not limited to the examples shown below.

[0073] FIG. 10 is a plan view illustrating a ground electrode provided on a first substrate of an antenna device of an antenna module according to a comparative example. As shown in FIG. 10 , a first ground electrode 181X according to the comparative example has a first portion 181Xa and a second portion 181Xb. In the example of FIG. 10 , the shape of the first ground electrode 181X is rectangular with a rectangular cutout when viewed from the front. In the comparative example, the geometric center C3 of the second portion 181Xb is located on the Z2 side of the geometric center C2 of the first portion 181Xa. Therefore, the geometric centers C2 and C3 are not on a line SA that passes through the geometric center C1X of the first ground electrode 181X and extends in the Y direction. Therefore, the shape of the ground electrode 180X of the antenna device of the antenna module according to the comparative example is not axisymmetric with respect to the line SA that passes through the geometric center C1X of the first ground electrode 181X and extends in the Y direction.

[0074] In the example, the ground electrode 180 includes a first ground electrode 181 according to the first embodiment and a second ground electrode 182. Therefore, the shape of the ground electrode 180 of the antenna device of the antenna module according to the example is symmetrical in the Z direction with respect to a line passing through the geometric center of the feed element 121 as the axis of symmetry.

[0075] Various simulations were performed to measure the cross polarization characteristics of the antenna modules according to the comparative example and the example. In the simulation results described below, only the two feed elements 121 on the Y1 direction side of the first substrate 131 were active.

[0076] Fig. 11 is a diagram showing the simulation results of the radiation pattern of the horizontally polarized wave component according to the comparative example. Fig. 12 is a diagram showing the simulation results of the radiation pattern of the horizontally polarized wave component according to the example. In the simulations of Fig. 11 and Fig. 12, the radiation electric field distribution was simulated when the antenna module was driven under uniform excitation conditions, i.e., with settings that radiate strongly in the front direction of the antenna (X1 direction).

[0077] Fig. 13 is a diagram showing the simulation results of the radiation pattern of the horizontally polarized wave component according to the comparative example. Fig. 14 is a diagram showing the simulation results of the radiation pattern of the horizontally polarized wave component according to the example. In the simulations of Fig. 13 and Fig. 14, the radiated electric field distribution when the antenna module is driven under beam scanning conditions was simulated.

[0078] Fig. 15 is a diagram showing the simulation results of the surface current distribution of the ground electrode of the antenna device of the antenna module according to the comparative example. Fig. 16 is a diagram showing the simulation results of the surface current distribution of the ground electrode of the antenna device of the antenna module according to the example. In the simulations according to Fig. 15 and Fig. 16, the surface current distribution of the ground electrode when the antenna module is driven under beam scanning conditions was simulated. Note that Fig. 15 and Fig. 16 show the simulation results in a diagram of the antenna module according to the comparative example or example viewed along the X1 direction.

[0079] 11 to 14, in the example in which the shape of the first ground electrode 181 is line-symmetrical with respect to the straight line SA that passes through the geometric center C1 of the first ground electrode 181 and extends in the Y direction as the axis of symmetry, the difference between the main polarization (Co-pol.) and the cross polarization (Cross-pol.) is larger than in the comparative example in which the shape of the first ground electrode 181X is not line-symmetrical with respect to the straight line SA that passes through the geometric center C1X of the first ground electrode 181X and extends in the Y direction as the axis of symmetry, and therefore it can be seen that the polarization characteristics are improved. In particular, under beam scanning conditions, in the example, the difference between the main polarization (Co-pol.) and the cross polarization (Cross-pol.) is even larger than in the comparative example, and therefore it can be seen that the polarization characteristics are further improved.

[0080] 15 and 16 , it can be seen that the example in which the shape of the first ground electrode 181 is line-symmetrical with respect to a straight line SA that passes through the geometric center C1 of the first ground electrode 181 and extends in the Y direction as the axis of symmetry has a surface current distribution that is symmetrical with respect to the Z direction, compared to the comparative example in which the shape of the first ground electrode 181X is not line-symmetrical with respect to a straight line that passes through the geometric center SA of the first ground electrode 181X as the axis of symmetry. From this, it is thought that making the shape of the first ground electrode 181 line-symmetrical with respect to the straight line SA can improve the cross polarization characteristics.

[0081] FIG. 17 is a schematic plan view illustrating surface current vectors in a ground electrode according to a comparative example. FIG. 18 is a schematic plan view illustrating surface current vectors in a ground electrode according to an example. FIGS. 17 and 18 show the ground electrodes corresponding to regions XVII and XVIII in FIGS. 15 and 16 , respectively. As shown in FIG. 17 , in the ground electrode 180X according to the comparative example, a component V1 occurs in the first portion 181Xa of the first ground electrode 181X, and the component V1 is line-symmetric about a line SA passing through the geometric center of the first ground electrode 181X and extending in the Y direction as the axis of symmetry. A component V2 flows from the first portion 181Xa to the second portion 181Xb, and the component V2 is not line-symmetric about the line SA passing through the geometric center of the first ground electrode 181X and extending in the Y direction as the axis of symmetry. As a result, it is believed that the distribution of the surface current in the ground electrode 180 according to the comparative example is not line-symmetric about the line SA. 18 , in the ground electrode 180 according to the example, only a component V1 that is line-symmetric with respect to a line SA that passes through the geometric center of the first ground electrode 181 and extends in the Y direction is generated in the first ground electrode 181. As a result, in the ground electrode 180 according to the example, it is considered that the distribution of the surface current is line-symmetric with respect to the line SA.

[0082] The above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the present invention. The present invention may be modified or improved without departing from the spirit thereof, and equivalents thereof are also included in the present invention.

[0083] The present invention can also take the following forms.

[0084] a first substrate on which the radiating elements and the ground electrode are provided, a second substrate having a normal direction different from that of the first substrate, and a bent portion connecting the first substrate and the second substrate; the first substrate having: a protruding portion including a portion that protrudes in a first direction along the first substrate toward the second substrate and a portion of the protruding portion in a direction opposite to the first direction; and a notched portion of the protruding portion that is a portion other than the protruding portion and is in a second direction along the first substrate and intersects with the first direction; the bent portion is connected to the first substrate at the notched portion; the ground electrode has a first ground electrode that is arranged to face the radiating elements provided on the protruding portion; and the shape of the first ground electrode is a straight line extending in the second direction and is axisymmetric with respect to a straight line that passes through the geometric center of the first ground electrode. (2) The antenna module according to (1), wherein the first ground electrode has: a first portion disposed opposite the radiating element; and a second portion provided in the cutout and connected to the first portion. (3) The antenna module according to (2), further comprising: a bent ground electrode provided on a surface or inside the bent portion and connected to a reference potential, wherein at least one of the second portions is connected to the bent ground electrode. (4) The antenna module according to (1), wherein the ground electrode further comprises a second ground electrode provided in the cutout and spaced apart from the first ground electrode. (5) The antenna module according to (4), further comprising: a bent ground electrode provided on a surface or inside the bent portion and connected to a reference potential, wherein at least one of the second ground electrodes is connected to the bent ground electrode. (6) The antenna module according to (4) or (5), wherein the minimum distance between the first ground electrode and the second ground electrode when viewed along a normal direction to the first substrate is equal to or greater than a quarter wavelength.(7) The antenna module according to (4) or (5), wherein, when viewed along the normal direction of the first substrate, a distance between the second ground electrode adjacent to the first ground electrode and the first ground electrode is not uniform. (8) The antenna module according to (7), wherein, when viewed along the normal direction of the first substrate, a maximum distance between the first ground electrode and the second ground electrode adjacent to the first ground electrode is equal to or greater than one-sixth of a wavelength. (9) The antenna module according to any one of (4) to (8), wherein a plurality of the second ground electrodes are provided in one of the cutout portions of the first substrate, and at least one second ground electrode is adjacent to another second ground electrode. (10) The antenna module according to (9), further comprising a bent ground electrode provided on a surface or inside the bent portion and connected to a reference potential, wherein at least one second ground electrode is connected to the bent ground electrode, and the at least one second ground electrode is not adjacent to the first ground electrode. (11) A communication device equipped with the antenna module according to any one of (1) to (10).

[0085] 10 Communication device 20 Mounting board 21 Surface 30 Housing 100 Antenna module 105 Dielectric substrate 110 RFIC 111A to 111D, 113A to 113D Switch 112AR to 112DR Low noise amplifier 112AT to 112DT Power amplifier 114A to 114D Attenuator 115A to 115D Phase shifter 116 Signal combiner / demultiplexer 117 Switch 118 Mixer 119 Amplifier circuit 120 Antenna device 121 Power feed element 131 First substrate 132 Second substrate 133 Protrusion 134 Notch side surface 135 Bent portion 136 Notch 140 Bump 171, 172 Power feed wiring 180, 180A to 180C, 180X Ground electrode 181, 181A, 181X First ground electrode 181a, 181Xa First part 181b, 181Xb Second part 182, 182B, 182C Second ground electrode 183 Ground electrode 184 Bent ground electrode 200 BBIC AR1 area SA straight line SP power supply point

Claims

1. A dielectric substrate, a plurality of radiating elements disposed on the dielectric substrate, and a ground electrode disposed on the dielectric substrate facing the radiating elements, wherein the dielectric substrate includes a first substrate provided with the radiating elements and the ground electrode, a second substrate having a different normal direction from the first substrate, and a bent portion connecting the first substrate and the second substrate; the first substrate includes a protruding portion protruding in a first direction along the first substrate toward the second substrate and a portion in a direction opposite to the first direction of the protruding portion; the portion other than the protruding portion has a notch portion in a second direction intersecting the first direction along the first substrate; the bent portion is connected to the first substrate at the notch portion; the ground electrode has a first ground electrode disposed facing the radiating element provided on the protruding portion; and the shape of the first ground electrode is a straight line extending in the second direction and is line-symmetric with a straight line passing through the geometric center of the first ground electrode as the axis of symmetry. Antenna module.

2. The first ground electrode has a first portion disposed facing the radiating element and a second portion provided in the notch portion and connected to the first portion. The antenna module according to claim 1.

3. Further comprising a bent ground electrode provided on the surface or inside of the bent portion and connected to the reference potential, and at least one of the second portions is connected to the bent ground electrode. The antenna module according to claim 2.

4. The ground electrode further has a second ground electrode provided in the notch portion and spaced apart from the first ground electrode. The antenna module according to claim 1.

5. Further comprising a bent ground electrode provided on the surface or inside of the bent portion and connected to the reference potential, and at least one of the second ground electrodes is connected to the bent ground electrode. The antenna module according to claim 4.

6. When viewed along the normal direction of the first substrate, the minimum distance between the first ground electrode and the second ground electrode is at least one-quarter wavelength. The antenna module according to claim 4 or 5.

7. When viewed along the normal direction of the first substrate, the distance between the second ground electrode adjacent to the first ground electrode and the first ground electrode is not uniform. The antenna module according to claim 4 or 5.

8. The antenna module according to claim 7, wherein, when viewed along the normal direction of the first substrate, the maximum distance between the first ground electrode and the second ground electrode adjacent to the first ground electrode is equal to or greater than one-sixth of the wavelength.

9. The antenna module according to any one of claims 4 to 8, wherein a plurality of the second ground electrodes are provided in one of the cutout portions of the first substrate, and at least one of the second ground electrodes is adjacent to another second ground electrode.

10. The antenna module according to claim 9, further comprising a bent ground electrode provided on the surface or inside of the bent portion and connected to a reference potential, wherein at least one of the second ground electrodes is connected to the bent ground electrode, and the at least one second ground electrode is not adjacent to the first ground electrode.

11. A communication device equipped with the antenna module according to any one of claims 1 to 10.

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