Antenna device, antenna module, and communication device

Abstract

This antenna device comprises: a rectangular dielectric substrate (130) in which a plurality of dielectric layers are laminated and which has two sets of opposing sides; at least one first radiation element (121) formed on the dielectric substrate (130); at least one second radiation element (122) disposed side by side with the at least one first radiation element (121) in a first direction that is orthogonal to the lamination direction of the dielectric substrate (130) and is parallel to one of the two sets of opposing sides; a ground electrode (GND1) disposed so as to face the at least one first radiation element (121) and the at least one second radiation element (122); and at least one peripheral electrode (150) formed in a plurality of layers between the at least one first radiation element (121) and the ground electrode (GND1), the at least one peripheral electrode (150) being electrically connected to the ground electrode (GND1) and the at least one second radiation element (122). When the dielectric substrate (130) is viewed in plan view from the lamination direction, a first end portion closer to a center line dividing the dielectric substrate (130) into two equal parts in the first direction, among the two end portions of the at least one second radiation element (122) in the second direction orthogonal to the lamination direction and the first direction, is open-ended.

Description

Antenna device, antenna module, and communication device

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

[0002] International Publication No. 2021 / 059661 (Patent Document 1) discloses an antenna device comprising a radiating element formed on a dielectric substrate, a ground electrode arranged opposite the radiating element, and a peripheral electrode formed in multiple layers between the radiating element and the ground electrode and electrically connected to the ground electrode.

[0003] International Publication No. 2021 / 059661

[0004] In an antenna device such as that disclosed in International Publication No. 2021 / 059661 (Patent Document 1), the use of peripheral electrodes suppresses degradation of antenna characteristics when the size and / or shape of the ground electrode are restricted.

[0005] However, the antenna device described in Patent Document 1 has a problem in that the direction of radio wave radiation is limited to the normal direction of the dielectric substrate.

[0006] The present disclosure has been made to solve such problems, and its purpose is to expand the radiation range of radio waves in an antenna device while suppressing degradation of antenna characteristics when the size and / or shape of the ground electrode is restricted.

[0007] The antenna device according to the present disclosure comprises: a rectangular dielectric substrate formed by stacking a plurality of dielectric layers and having two pairs of opposing sides; at least one first radiating element formed on the dielectric substrate; at least one second radiating element arranged alongside the at least one first radiating element in a first direction that is orthogonal to the stacking direction of the dielectric substrate and parallel to one of the two pairs of opposing sides; a ground electrode arranged opposite the at least one first radiating element and the at least one second radiating element; and at least one peripheral electrode formed on a plurality of layers between the at least one first radiating element and the ground electrode and electrically connected to the ground electrode and the at least one second radiating element, wherein, when the dielectric substrate is viewed in a plane from the stacking direction, of both end portions of the at least one second radiating element in a second direction orthogonal to the stacking direction and the first direction, a first end portion closer to a midline that divides the dielectric substrate into two equal parts in the first direction is an open end.

[0008] According to the present disclosure, in an antenna device, it is possible to expand the radiation range of radio waves while suppressing degradation of antenna characteristics when the size and / or shape of the ground electrode is restricted.

[0009] 12 is a block diagram of a communication device to which an antenna module according to a first embodiment is applied. 13 is a plan view showing a part of the antenna module according to the first embodiment. 14 is a plan view showing the entire antenna module of FIG. 2. 15 is a side perspective view of the antenna module of FIG. 2. 16 is a perspective view of the antenna module of FIG. 2 in the vicinity of a peripheral electrode. 17 is a diagram for explaining the state of electric field lines between a first radiating element and a ground electrode in the absence of a peripheral electrode. 18 is a diagram for explaining the state of electric field lines between a first radiating element and a ground electrode in the presence of a peripheral electrode. 19 is a diagram for explaining the state of electric field lines between a first radiating element and a ground electrode in the presence of a peripheral electrode. 20 is a diagram for explaining simulation results of antenna characteristics in a first arrangement pattern. 21 is a diagram for explaining simulation results of antenna characteristics in a second arrangement pattern. 22 is a diagram for explaining simulation results of antenna characteristics in a third arrangement pattern. 23 is a plan view showing the entire antenna module according to a second embodiment. 24 is a diagram for explaining simulation results of antenna characteristics of the antenna module according to the second embodiment and of a comparative example in the millimeter wave band having a center frequency of 39 GHz. 25 is a plan view showing the entire antenna module according to a third embodiment. 26 is a diagram for explaining the configuration of a feed line of a second radiating element in the antenna module of FIG. 2. 27 is a diagram for explaining a modification of the antenna module of FIG. 2. 28 is a graph comparing the simulation results of the simulation results of the antenna module according to FIG. 22 as cumulative distribution functions.

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, identical or corresponding parts are designated by the same reference numerals, and their description will not be repeated. It is assumed that the embodiments and modifications of the present disclosure can be combined with each other.

[0011] [First Embodiment] (Basic Configuration of Communication Device) Fig. 1 is an example of a block diagram of a communication device 10 to which an antenna module 100 according to the 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 present embodiment is millimeter-wave radio waves with center frequencies of 28 GHz, 39 GHz, and 60 GHz, but radio waves in other frequency bands are also applicable.

[0012] 1 , a 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 to a high-frequency signal in the RFIC 110 and radiates the signal from the antenna device 120. The communication device 10 also transmits a high-frequency signal received by the antenna device 120 to the RFIC 110, downconverts the signal, and processes it in the BBIC 200.

[0013] 1 , for ease of explanation, only two first radiating elements 121 and two second radiating elements 122 are shown among the multiple first radiating elements (first feed elements) 121 and multiple second radiating elements (second feed elements) 122 that constitute the antenna device 120. However, the antenna device 120 may include three or more first radiating elements 121 and three or more second radiating elements 122. Alternatively, the number of each of the first radiating elements 121 and second radiating elements 122 provided in the antenna device 120 may be one.

[0014] In this embodiment, the first radiating element 121 constitutes a patch antenna having a flat plate shape, and the second radiating element constitutes a planar inverted-F antenna (PIFA).

[0015] 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.

[0016] 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.

[0017] The signal transmitted from BBIC 200 is amplified by amplifier circuit 119 and up-converted by mixer 118. The up-converted transmission signal, which is a high-frequency signal, is split into four by signal combiner / splitter 116 and passes through four signal paths to be fed to different first radiating elements 121 and second radiating elements 122. At this time, the phase shift degrees of phase shifters 115A to 115D arranged on each signal path are individually adjusted, thereby adjusting the directivity of antenna device 120.

[0018] The received signals, which are high-frequency signals received by each of the first radiating elements 121 and each of the second radiating elements 122, respectively 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.

[0019] The RFIC 110 is formed, for example, as a one-chip integrated circuit component including the above circuit configuration. Alternatively, the devices (switches, power amplifiers, low-noise amplifiers, attenuators, phase shifters) corresponding to each first radiating element 121 in the RFIC 110 may be formed as one-chip integrated circuit components for each corresponding first radiating element 121. Similarly, the devices (switches, power amplifiers, low-noise amplifiers, attenuators, phase shifters) corresponding to each second radiating element 122 in the RFIC 110 may be formed as one-chip integrated circuit components for each corresponding second radiating element 122.

[0020] (Configuration of Antenna Module) Next, the configuration of the antenna module 100 according to the first embodiment will be described in detail with reference to FIGS.

[0021] Fig. 2 is a plan view showing a portion of the antenna module 100 according to the first embodiment. Fig. 3 is a plan view showing the entire antenna module 100 of Fig. 2. Fig. 4 is a side perspective view of the antenna module 100 of Fig. 2. Fig. 5 is a perspective view of the vicinity of the peripheral electrode 150 of the antenna module 100 of Fig. 2. Note that in the plan views of Figs. 2 and 3, the dielectric layer is omitted so that the internal electrodes can be seen.

[0022] 2 to 5, the antenna module 100 includes a dielectric substrate 130, power supply wiring 140, 141, a peripheral electrode 150, a power supply electrode 180, and ground electrodes GND1, GND2, in addition to the first radiating element 121, the second radiating element 122, and the RFIC 110. In the following description, the normal direction of the dielectric substrate 130 is defined as the Z-axis direction, and planes perpendicular to the Z-axis direction are defined as the X-axis and the Y-axis. In addition, the positive direction of the Z-axis in each figure may be referred to as the upper side, and the negative direction of the Z-axis may be referred to as the lower side.

[0023] The dielectric substrate 130 may be, 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. The dielectric substrate 130 is an example of a rectangular dielectric substrate having two sets of opposing sides and formed by laminating multiple dielectric layers.

[0024] The dielectric substrate 130 has a substantially rectangular shape. Hereinafter, the surface of the dielectric substrate 130 in the positive direction of the Z axis will be referred to as the upper surface, the surface of the dielectric substrate 130 in the negative direction of the Z axis will be referred to as the lower surface, and the surfaces perpendicular to the upper and lower surfaces will be referred to as side surfaces.

[0025] 2, the first radiating element 121 has an octagonal shape. The feed point SP1 of the first radiating element 121 is disposed at a position offset from the face center CP of the first radiating element 121 by an equal distance in the negative direction of the X axis and the positive direction of the Y axis. Therefore, in the antenna module 100, the polarization direction is the direction of the dashed line CL1 in FIG. 2.

[0026] As shown in FIG. 3 , when the dielectric substrate 130 is viewed in a plan view from the normal direction (Z-axis direction), multiple peripheral electrodes 150 are arranged on both ends of the dielectric substrate 130 in the Y-axis direction. When the dielectric substrate 130 is viewed in a plan view from the normal direction (Z-axis direction), the peripheral electrodes 150 have a trapezoidal shape. Each of the multiple peripheral electrodes 150 is arranged along a side of the first radiating element 121 that is aligned with the polarization direction and a side that is perpendicular to the polarization direction. In other words, the oblique side of the peripheral electrode 150 is arranged to face a side of the first radiating element 121 that is aligned with the polarization direction or a side that is perpendicular to the polarization direction. The multiple peripheral electrodes 150 are arranged to surround the first radiating element 121 on all sides.

[0027] The second radiating element 122 is disposed on a peripheral electrode 150 located at one of both ends in the Y-axis direction of the dielectric substrate 130. The second radiating element 122 has, for example, a flat plate shape. As shown in Fig. 3 , the first radiating elements 121 and the second radiating elements 122 are disposed alternately in the X-axis direction on the dielectric substrate 130.

[0028] The antenna module 100 includes two first radiating elements 121 arranged side by side in a first direction (X-axis direction). The second radiating element 122 is arranged between the two first radiating elements 121. The second radiating element 122 is an example of a second radiating element arranged side by side with the first radiating element in the first direction (X-axis direction) that is orthogonal to the stacking direction of the dielectric substrate and parallel to one pair of two pairs of opposing sides.

[0029] 4, the first radiating element 121 is formed on a layer (an upper layer) close to the top surface 131 of the dielectric substrate 130. The first radiating element 121 may be exposed on the top surface 131 of the dielectric substrate 130, or may be disposed on an internal layer of the dielectric substrate 130. Note that in the first embodiment, for ease of explanation, a case where a feed element is used as the first radiating element 121 will be described as an example, but the first radiating element 121 may also be a parasitic element and / or a parasitic element.

[0030] The second radiating element 122 is formed on a layer below the layer on which the first radiating element 121 is arranged. The second radiating element 122 may be arranged on the same layer as the first radiating element 121.

[0031] A flat-plate-shaped ground electrode GND2 is arranged on a layer (lower layer) of the dielectric substrate 130 that is closer to the bottom surface 132 than the first radiating element 121 and the second radiating element 122, facing the first radiating element 121 and the second radiating element 122. A ground electrode GND1 is arranged on a layer between the first radiating element 121 and the second radiating element 122 and the ground electrode GND2.

[0032] The layer between the ground electrode GND1 and the ground electrode GND2 is used as a wiring area. A wiring pattern 170 is arranged in the wiring area. The wiring pattern 170 forms a power feed wiring for supplying a high-frequency signal to the first radiating element 121 or the second radiating element 122, stubs and filters connected to the power feed wiring, and connection wiring for connecting to other electronic components. In this way, by forming the wiring area on the dielectric layer on the opposite side of the ground electrode GND1 from the first radiating element 121 and the second radiating element 122, unnecessary coupling between the first radiating element 121 or the second radiating element 122 and each wiring pattern 170 can be suppressed.

[0033] The RFIC 110 is mounted on the lower surface 132 of the dielectric substrate 130 via solder bumps 160. The RFIC 110 may be connected to the dielectric substrate 130 using a multi-pole connector instead of solder connection.

[0034] Fig. 15 is a diagram showing a modification of the antenna module 100 of Fig. 2. As shown in Fig. 15, a SiP (System In Package) module 1000 including an RFIC 110 may be provided on the lower surface 132 of a dielectric substrate 130. In addition to the RFIC 110, the SiP module 1000 may also be provided with a power module IC 1010 and a power inductor 1020.

[0035] The peripheral electrodes 150 are formed on multiple dielectric layers between the first radiating element 121 and the ground electrode GND1. The peripheral electrodes 150 are electrically connected to the ground electrode GND1 and the second radiating element 122. When the dielectric substrate 130 is viewed from above, the peripheral electrodes 150 are arranged so as to overlap in the stacking direction. That is, the peripheral electrodes 150 form virtual conductor walls along each side of the dielectric substrate 130. Adjacent peripheral electrodes 150 in the stacking direction are electrically connected by vias 151. Furthermore, the bottom peripheral electrode 150 is electrically connected to the ground electrode GND1 by the via 151. That is, the peripheral electrodes 150 are essentially configured equivalently to a configuration in which the end of the ground electrode GND1 is extended in the stacking direction. In this way, the peripheral electrodes 150 are electrically connected to the second radiating element 122 and the ground electrode GND1. Note that the peripheral electrodes 150 stacked in the stacking direction do not need to have the same shape. For example, the size of the peripheral electrode 150 may increase as it approaches the ground electrode GND1 in the stacking direction of the dielectric substrate 130.

[0036] In the antenna module 100, the vias 151 formed in adjacent dielectric layers in the stacking direction are preferably positioned so as not to overlap each other when viewed in a plan view from the normal direction of the dielectric substrate 130. The conductive material (typically copper) forming the vias 151 has a lower compressibility when pressurized than the dielectric material. Therefore, if the vias 151 in each layer are all positioned in the same position when viewed in a plan view from the normal direction of the dielectric substrate 130, when the dielectric substrate 130 is pressed to bond the dielectric layers, the thickness reduction rate of the via 151 portion will be smaller than that of the other dielectric portions, which may cause variations in the overall thickness of the dielectric substrate 130. Therefore, by positioning the vias 151 in adjacent dielectric layers in the stacking direction at different positions as described above, the thickness accuracy of the molded dielectric substrate 130 can be improved.

[0037] The electrical connections between the peripheral electrodes 150 and between the peripheral electrode 150 and the ground electrode GND1 are not limited to direct connections through the vias 151, and may be configured such that part or all of the connections are capacitively coupled. Furthermore, the peripheral electrode 150 may not be formed by connecting individual elements, but may be formed as an integrated element.

[0038] As shown in Fig. 4, a second radiating element 122 is disposed on one of peripheral electrodes 150 provided on both ends of dielectric substrate 130. As shown in Figs. 4 and 5, second radiating element 122 has a feed point SP2 and a short-circuit point SP3. Second radiating element 122 is connected to peripheral electrode 150 at short-circuit point SP3. Short-circuit point SP3 and peripheral electrode 150 are connected via via 151.

[0039] A high frequency signal is supplied from the RFIC 110 to a feed point SP1 of the first radiating element 121 via the feed wiring 140. The feed wiring 140 rises from the RFIC 110, penetrating the ground electrode GND2, and extends through a wiring region. The feed wiring 140 rises from directly below the first radiating element 121, penetrating the ground electrode GND1, and is connected to the feed point SP1 of the first radiating element 121.

[0040] A high-frequency signal is supplied from the RFIC 110 to a feed point SP2 of the second radiating element 122 via a feed wiring 141 and a feed electrode 180. The feed wiring 141 rises from the RFIC 110, penetrating the ground electrode GND2, and extends through the wiring area. The feed wiring 141 rises, penetrating the ground electrode GND1, and is connected to the feed electrode 180. A plurality of feed electrodes 180 are provided between the second radiating element 122 and the ground electrode GND1. Each of the plurality of feed electrodes 180 is connected by a via 181. Note that the feed point SP2 and the wiring area may be connected by a feed wiring, similar to the configuration between the feed point SP1 and the wiring area.

[0041] As shown in Figures 3 and 5, when the dielectric substrate 130 is viewed in a plane from the stacking direction, of the two end portions of the second radiating element 122 in the second direction (Y-axis direction) perpendicular to the stacking direction and the first direction (X-axis direction), the first end portion 122a closer to the midline CL2 that divides the dielectric substrate into two equal parts in the first direction is an open end.

[0042] The second radiating element 122 has a second end 122b opposite to the first end 122a, which is connected to the peripheral electrode 150. The second end 122b is provided with a short point SP3. The short point SP3 is grounded to the ground electrode GND1 via the peripheral electrode 150.

[0043] In this way, the second radiating element 122 is a "single-sided ground patch." The second radiating element 122 is fed at a feed point SP2. Therefore, the second radiating element 122 constitutes a planar inverted-F antenna 190, with the peripheral electrode 150 as a short-circuiting element and the feed wiring 141 and the feed electrode 180 as feed elements. By adjusting the size of the second radiating element 122 in the Y-axis direction, the frequency band of the planar inverted-F antenna 190 can be set to an appropriate range.

[0044] 3, when viewed from above in the normal direction of the dielectric substrate 130, the second radiating element 122 constituting the planar inverted-F antenna 190 is disposed at a position that does not overlap with the first radiating element 121. A line connecting the first end 122a (see FIG. 5) and the second end 122b (see FIG. 5) of the second radiating element 122 intersects with the arrangement direction (X-axis direction) of the multiple first radiating elements 121. In addition, the peripheral electrode 150 is formed so as to be elongated in the arrangement direction of the multiple first radiating elements 121.

[0045] (Usefulness of Peripheral Electrodes) Generally, in a patch antenna having a flat radiating element such as the first radiating element 121, radio waves are radiated by electromagnetic field coupling between the radiating element and the ground electrode. In order to achieve desired antenna characteristics in such a patch antenna, it is necessary to arrange a ground electrode with a sufficiently large area relative to the radiating element.

[0046] On the other hand, there is still a strong demand for smaller and thinner mobile terminals such as mobile phones and smartphones that use patch antennas, and as a result, there is a need to further reduce the size of the built-in antenna devices.

[0047] However, when an antenna device is placed in a limited space within a housing, it may not be possible to make the ground electrode sufficiently wide relative to the radiating element. Furthermore, depending on the installation location of the antenna device or its position relative to peripheral devices, it may not be possible to make the ground electrode symmetrical. If the size and shape of the ground electrode are restricted in this way, the electric field lines between the radiating element and the ground electrode may become distorted, which may affect antenna characteristics such as gain, frequency band, and directivity.

[0048] Therefore, in the first embodiment, one of the purposes of the antenna module is to suppress the degradation of antenna characteristics when the size and / or shape of the ground electrode is limited, and the antenna module is provided with a peripheral electrode 150. The reasons why the peripheral electrode 150 is useful for achieving this purpose will be explained below.

[0049] Fig. 6 is a diagram for explaining the state of the electric field lines between the first radiating element 121 and the ground electrode GND1 when there is no peripheral electrode 150. Fig. 7 is a diagram for explaining the state of the electric field lines between the first radiating element 121 and the ground electrode GND1 when there is a peripheral electrode 150. Note that Figs. 6 and 7 are cross-sectional views obtained when cutting the dielectric substrate 130 in the YZ plane at a portion that does not include the second radiating element 122.

[0050] When a high-frequency signal is supplied to the first radiating element 121, electromagnetic field coupling occurs between the end of the first radiating element 121 and the ground electrode GND1. At this time, electric field lines are emitted from one end of the first radiating element 121 toward the ground electrode GND1, and the other end receives electric field lines from the ground electrode GND1.

[0051] When the area of ​​the ground electrode GND1 is sufficiently large relative to the first radiating element 121, electric field lines are exchanged on the surface of the ground electrode GND1 facing the first radiating element 121. However, when the area of ​​the ground electrode GND1 is not sufficiently large, some of the electric field lines may wrap around the back surface of the ground electrode GND1, as shown in Fig. 6. This may increase the proportion of radio waves radiated to the back surface of the antenna device, disrupting the directivity and potentially degrading the antenna gain in the desired direction, narrowing the frequency bandwidth, or causing fluctuations in the polarization direction, such as circular polarization.

[0052] In the antenna module 100 according to the first embodiment, as shown in Fig. 7 , a peripheral electrode 150 electrically connected to the ground electrode GND1 is disposed in a layer between the first radiating element 121 and the ground electrode GND1. Because the distance between the peripheral electrode 150 and the first radiating element 121 is shorter than the distance between the ground electrode GND1 and the first radiating element 121, the degree of electromagnetic coupling between the peripheral electrode 150 and the first radiating element 121 is stronger than that between the peripheral electrode 150 and the ground electrode GND1. Therefore, the electric field lines that wrap around the back side of the ground electrode GND1 in Fig. 6 are generated between the peripheral electrode 150 and the ground electrode GND1 in Fig. 7 . This suppresses radio wave radiation to the back side of the antenna device, thereby suppressing degradation of antenna characteristics such as gain.

[0053] The peripheral electrode 150 is disposed symmetrically with respect to the polarization direction of the radio wave and / or a direction perpendicular to the polarization direction. This improves the symmetry of the electric field lines generated between the first radiating element 121 and the ground electrode GND1. By disposing the peripheral electrode 150 symmetrically with respect to the polarization direction of the radio wave and / or a direction perpendicular to the polarization direction, it is possible to increase the degree of coupling between the first radiating element 121 and the ground electrode GND1 and improve the symmetry of the electric field lines generated between the first radiating element 121 and the ground electrode GND1. As a result, it is possible to suppress degradation of the antenna characteristics.

[0054] (Usefulness of an inverted-F antenna including a peripheral electrode) As described above, according to the first embodiment, by disposing the peripheral electrode 150 in addition to the first radiating element 121 in the antenna module 100, it is possible to suppress degradation of the antenna characteristics when the size and / or shape of the ground electrode is restricted. However, if the antenna module 100 is provided with only the first radiating element 121 as a radiating element, the radiation direction of radio waves from the antenna module 100 is limited to the normal direction of the dielectric substrate 130 (the positive direction of the Z axis).

[0055] Generally, in order to expand the radiation range of radio waves in an antenna module equipped with a patch antenna, it is considered to arrange a dipole antenna around the patch antenna provided on a dielectric substrate. This allows the antenna module to radiate radio waves not only in the normal direction of the dielectric substrate but also in the lateral direction of the dielectric substrate (direction perpendicular to the normal direction of the dielectric substrate). Therefore, in order to expand the radiation range of radio waves, it is also considered to adopt an improvement plan in which a dipole antenna is arranged in the antenna module 100 in addition to the first radiating element 121.

[0056] However, such an improvement requires an area for arranging the dipole antenna, which requires increasing the size of the dielectric substrate 130. This does not meet the need for miniaturization of antenna devices and antenna modules.

[0057] Therefore, in the first embodiment, it is proposed to utilize the free space created by arranging the peripheral electrode 150 and the peripheral electrode 150 to arrange the planar inverted-F antenna 190 on the dielectric substrate 130 .

[0058] 4 and 5 , in the first embodiment, peripheral electrode 150 functions as a short-circuiting element of planar inverted-F antenna 190. Therefore, peripheral electrode 150, which is used to suppress degradation of antenna characteristics, is utilized as a short-circuiting element of planar inverted-F antenna 190 in the first embodiment.

[0059] Furthermore, the second radiating element 122 constituting the planar inverted-F antenna 190 is disposed in an empty space on the dielectric substrate 130 that is created in order to place the peripheral electrode 150 next to the first radiating element 121. In other words, in the first embodiment, the empty space that is created in order to place the peripheral electrode 150 next to the first radiating element 121 is utilized as an area for placing the second radiating element 122.

[0060] As described above, in the first embodiment, the planar inverted-F antenna 190 is disposed on the dielectric substrate 130 by utilizing the peripheral electrode 150 and the free space created by disposing the peripheral electrode 150. The planar inverted-F antenna 190 radiates radio waves in a direction different from the normal direction of the dielectric substrate 130, as the peripheral electrode 150 functions as a short-circuiting element. More specifically, the second radiating element 122 constituting the planar inverted-F antenna 190 radiates radio waves in the lateral direction of the dielectric substrate 130, particularly in the Y-axis direction or in a direction around the Y-axis.

[0061] As a result, the antenna module 100 according to the first embodiment can expand the radiation range of radio waves while suppressing degradation of antenna characteristics when the size and / or shape of the ground electrode is restricted.

[0062] (Radiation Direction of Radio Waves from Second Radiating Element) Hereinafter, the radiation direction of radio waves from second radiating element 122 constituting planar inverted-F antenna 190 will be described in more detail with reference to FIGS. 8 to 10. FIG.

[0063] Fig. 8 is a diagram showing a simulation result of antenna characteristics in the first arrangement pattern, Fig. 9 is a diagram showing a simulation result of antenna characteristics in the second arrangement pattern, and Fig. 10 is a diagram showing a simulation result of antenna characteristics in the third arrangement pattern.

[0064] In any of the first to third arrangement patterns, the short point SP3 of the second radiating element 122 is grounded to the ground electrode GND1, and power is fed to the feed point SP2 of the second radiating element 122. That is, in any of the first to third arrangement patterns, the second radiating element 122 functions as a planar inverted-F antenna.

[0065] 8 to 10 show the gain distribution in (A), and the electric field distribution in (B). The different types of hatching in each gain distribution indicate different gain levels. Similarly, the different types of hatching in each electric field distribution indicate different electric field strengths.

[0066] First, the gain distribution and electric field distribution in the first arrangement pattern will be described with reference to FIG. 8 . In the first arrangement pattern, the second radiating element 122 is arranged on a dielectric substrate 130 on which the first radiating element 121 and peripheral electrode 150 are not arranged. As shown in FIG. 8A , in the first arrangement pattern, the second radiating element 122 radiates a strong radio wave at least in the positive direction of the Z axis. However, in the first arrangement pattern, the second radiating element 122 does not radiate a radio wave in the Y axis direction with the same intensity as seen in the positive direction of the Z axis. As shown in FIG. 8B , in the first arrangement pattern, a strong electric field is generated on the side of the second radiating element 122 in the Y axis direction that is farther from the end of the dielectric substrate 130, i.e., near the open end of the second radiating element 122 that constitutes the planar inverted-F antenna (see the circled area in FIG. 8B ).

[0067] Next, the gain distribution and electric field distribution in the second arrangement pattern will be described with reference to Fig. 9. In the second arrangement pattern, the second radiating element 122 is arranged on the dielectric substrate 130 on which two first radiating elements 121 are arranged side by side in the X-axis direction with the peripheral electrode 150 sandwiched therebetween. The second radiating element 122 is arranged on the peripheral electrode 150. In other words, the second arrangement pattern is included in the antenna module 100 shown in Fig. 3. However, the gain distribution and electric field distribution shown in Fig. 9 are simulation results obtained when it is set so that no power is supplied to the first radiating element 121.

[0068] As shown in Figure 9(A), in the second arrangement pattern, the second radiating element 122 emits a strong radio wave at least in the negative direction of the Y axis. The negative direction of the Y axis corresponds to the direction perpendicular to the normal direction of the dielectric substrate 130 (the lateral direction of the dielectric substrate 130). As shown in Figure 9(B), in the second arrangement pattern, a strong electric field is generated near the open end of the planar inverted-F antenna formed by the second radiating element 122 and in the peripheral electrode 150 (see the circled area in Figure 9(B)). In particular, a strong electric field is generated in the portion of the peripheral electrode 150 close to the first radiating element 121.

[0069] As can be seen from the simulation results shown in Figures 8 and 9, the second radiating element 122 radiates strong radio waves in the lateral direction of the dielectric substrate 130 in the second arrangement pattern. Therefore, according to the antenna module 100 having a configuration similar to the second arrangement pattern, the second radiating element 122 radiates strong radio waves in the lateral direction of the dielectric substrate 130. It goes without saying that the antenna module 100 radiates strong radio waves in the normal direction of the dielectric substrate 130 by feeding power to the first radiating element 121. Therefore, according to the antenna module 100, the radio wave radiation range can be expanded.

[0070] Next, the gain distribution and electric field distribution in the third arrangement pattern will be described with reference to Fig. 10. In the third arrangement pattern, one of the two first radiating elements 121 is removed from the second arrangement pattern shown in Fig. 9. The gain distribution and electric field distribution shown in Fig. 10 are simulation results obtained when the first radiating element 121 is set not to be fed with power.

[0071] As shown in Figure 10(A), in the third arrangement pattern, the second radiating element 122 radiates strong radio waves at least in the negative direction of the Y axis. Note that in the third arrangement pattern, the second radiating element 122 also radiates strong radio waves in the X axis direction. As shown in Figure 10(A), in the third arrangement pattern, a strong electric field is generated near the open end of the planar inverted-F antenna formed by the second radiating element 122 and in the peripheral electrode 150 (see the circled area in Figure 10(B)). In particular, a strong electric field is generated around the end of the peripheral electrode 150 (including the portion close to the first radiating element 121).

[0072] 10 , the second radiating element 122 also radiates strong radio waves in the lateral direction of the dielectric substrate 130 in the third arrangement pattern. Therefore, the configuration of the antenna module 100 may be the configuration shown in the third arrangement pattern instead of the configuration shown in the second arrangement pattern. That is, the antenna module 100 is required to include at least one first radiating element 121, one second radiating element 122, and one peripheral electrode 150.

[0073] Let us consider why the second radiating element 122 radiates radio waves in the lateral direction of the dielectric substrate 130 in the second and third arrangement patterns. First, when only the second radiating element 122 is arranged on the dielectric substrate 130, as in the first arrangement pattern, the electric field is concentrated near the open end of the second radiating element 122 that constitutes the planar inverted-F antenna. At this time, radio waves are radiated in the normal direction of the dielectric substrate 130.

[0074] In the second and third arrangement patterns, the peripheral electrode 150 is used as a short-circuit portion of the planar inverted-F antenna. In the second and third arrangement patterns, the electric field is concentrated not only at the open end of the second radiating element 122 but also at the peripheral electrode 150. In particular, the electric field is concentrated in the portion of the peripheral electrode 150 close to the first radiating element 121. In this way, the electric field distribution state changes between the first arrangement pattern and the second or third arrangement pattern.

[0075] When switching from the first arrangement pattern to the second arrangement pattern, the radiation direction of the radio waves is tilted from the normal direction of the dielectric substrate 130 toward the short-circuited portion of the planar inverted-F antenna, i.e., toward the side surface of the dielectric substrate 130. The same can be said when switching from the first arrangement pattern to the third arrangement pattern.

[0076] Therefore, it is considered that the change in the electric field distribution caused the radiation direction of the radio wave from the second radiating element 122 to change from the normal direction to the dielectric substrate 130 to the lateral direction.

[0077] As described above, according to the first embodiment, by arranging the second radiating element 122 in the second arrangement pattern or the third arrangement pattern on the dielectric substrate 130 on which the first radiating element 121 and the peripheral electrode 150 are arranged, it is possible to expand the radiation range (communication range) of the antenna module 100. Furthermore, in the first embodiment, the peripheral electrode 150 and the free space created by arranging the peripheral electrode 150 are utilized. Therefore, in the first embodiment, it is possible to increase the radiation surface without unnecessarily expanding the area.

[0078] 11 is a plan view showing the entire antenna module 100A according to the second embodiment. In the antenna module 100A according to the second embodiment, second radiating elements 122 are arranged at both ends in the Y-axis direction of the dielectric substrate 130. In this respect, the antenna module 100A according to the second embodiment differs from the antenna module 100 according to the first embodiment.

[0079] According to the antenna module 100 according to the first embodiment already described, radio waves are radiated in the normal direction and lateral directions of the dielectric substrate 130. More specifically, the antenna module 100 can radiate radio waves in the normal direction of the dielectric substrate 130 and in the negative direction of the Y axis. However, the antenna module 100 cannot radiate radio waves in the positive direction of the Y axis.

[0080] In the antenna module 100A according to the second embodiment, when the dielectric substrate 130 is viewed in plan from the stacking direction, two peripheral electrodes 150 are arranged to face each other in the second direction (Y-axis direction), and a second radiating element 122 is arranged on each of the two peripheral electrodes 150. According to the antenna module 100A according to the second embodiment, radio waves can be radiated in both the positive and negative directions of the Y-axis.

[0081] FIG. 12 is a diagram showing simulation results of the antenna characteristics of the antenna module 100A according to the second embodiment and the antenna characteristics of the comparative example in the millimeter wave band with a center frequency of 39 GHz.

[0082] Fig. 12(A) shows a contour diagram corresponding to the case where the planar inverted-F antenna 190 is not provided on the dielectric substrate 130. The contour diagram shown in Fig. 12(A) shows the gain distribution when the second radiating element 122 functioning as the planar inverted-F antenna 190 is removed from the antenna module 100 according to the first embodiment.

[0083] Fig. 12(B) shows a contour diagram corresponding to the case where the planar inverted-F antenna 190 is provided on one end side of the dielectric substrate 130. The contour diagram shown in Fig. 12(B) shows the gain distribution of the antenna module 100 according to the first embodiment.

[0084] Fig. 12(C) shows a contour diagram corresponding to the case where the planar inverted-F antenna 190 is provided on both end sides of the dielectric substrate 130. The contour diagram shown in Fig. 12(C) shows the gain distribution of the antenna module 100A according to the second embodiment.

[0085] 12A to 12C, the horizontal axis represents the angle θ from the X-axis direction around the Y-axis, and the vertical axis represents the angle φ from the Y-axis direction around the X-axis. Different types of hatching indicate different levels of gain.

[0086] 12A, a case will be described in which the planar inverted-F antenna 190 is not provided on the dielectric substrate 130. In this case, radio waves are radiated in the normal direction (Z-axis direction) of the dielectric substrate 130, but are not radiated in the lateral direction (Y-axis direction) of the dielectric substrate 130. Note that radio waves traveling in the normal direction of the dielectric substrate 130 are radiated by the first radiating element 121.

[0087] 12B, a case where a planar inverted-F antenna 190 is provided on one end side of the dielectric substrate 130, i.e., the case of the antenna module 100, will be described. In this case, radio waves are emitted not only in the normal direction of the dielectric substrate 130 but also in the negative direction of the Y axis (see the dashed frame).

[0088] 12C, a case where planar inverted-F antennas 190 are provided on both ends of the dielectric substrate 130, i.e., the case of the antenna module 100A, will be described. In this case, radio waves are emitted not only in the normal direction of the dielectric substrate 130 but also in the negative and positive directions of the Y axis (see dashed lines). Therefore, the antenna module 100A according to the second embodiment can provide greater coverage on both ends of the dielectric substrate 130 than the antenna module 100 according to the first embodiment.

[0089] FIG. 16 is a graph comparing the cumulative distribution functions (CDFs) of the simulation results of FIGS. 12A to 12C. The gain values ​​around 50%, indicated by the dashed line in FIG. 16, are compared for the first embodiment (FIG. 12B), the second embodiment (FIG. 12C), and the comparative example (FIG. 12A). In this case, as shown in FIG. 16, the gain values ​​for the first and second embodiments are higher than those for the comparative example. This result also shows that the antenna module 100 according to the first embodiment and the antenna module 100A according to the second embodiment are able to expand coverage compared to the comparative example.

[0090] Moreover, in the case of the antenna module 100A, the free space created by disposing the peripheral electrodes 150 at both ends of the dielectric substrate 130 and the peripheral electrodes 150 at both ends are utilized. Therefore, the antenna module 100A can expand the radiation range of radio waves while making better use of the free space of the dielectric substrate 130 and the peripheral electrodes 150 than the antenna module 100. The antenna module 100A according to the second embodiment is applied to the communication device 10 in the same way as the antenna module 100 according to the first embodiment.

[0091] [Embodiment 3] Fig. 13 is a plan view showing the entire antenna module 100B according to embodiment 3. Fig. 14 is a diagram showing the configuration of the feed line of the second radiating element 122 in the antenna module 100B of Fig. 13. In embodiment 3, a dual-band type antenna module 100B will be described.

[0092] 13, the antenna module 100B includes a third radiating element 123 in addition to the first radiating element 121 and the second radiating element 122. In this respect, the antenna module 100B according to the third embodiment differs from the antenna module 100 according to the first embodiment. Note that the antenna module 100A according to the second embodiment may be provided with the third radiating element 123 as shown in FIG.

[0093] The third radiating element 123 is stacked on the first radiating element 121 with a dielectric layer in between. The third radiating element 123 has a flat plate shape. When viewed from above in the normal direction of the dielectric substrate 130, the third radiating element 123 has a circular shape.

[0094] In the antenna module 100B, for example, the first radiating element 121 is a parasitic element, and the third radiating element 123 is a fed element. The feed point SP4 of the third radiating element 123 is provided at a position corresponding to the feed point SP1 of the first radiating element 121 according to the first embodiment. The feed wiring from the RFIC 110 passes through the first radiating element 121, which is a parasitic element, and is connected to the feed point SP4.

[0095] The dimension in the polarization direction of the third radiating element 123 is smaller than the dimension in the polarization direction of the first radiating element 121. Therefore, the resonant frequency of the third radiating element 123 is higher than the resonant frequency of the first radiating element 121.

[0096] When a high-frequency signal corresponding to the resonant frequency of the first radiating element 121 is supplied from the RFIC 110 to the feed point SP4, radio waves in a first frequency band corresponding to the resonant frequency are radiated from the first radiating element 121. When a high-frequency signal corresponding to the resonant frequency of the third radiating element 123 is supplied from the RFIC 110 to the feed point SP4, radio waves in a second frequency band corresponding to the resonant frequency are radiated from the third radiating element 123. The first frequency band may be, for example, 28 GHz. In this case, the second frequency band may be, for example, 39 GHz.

[0097] The size of the second radiating element 122 in the Y-axis direction is adjusted so that it can cover the frequency band of the radio waves radiated from the first radiating element 121 and the frequency band of the radio waves radiated from the third radiating element 123.

[0098] 14 , a diplexer 135 is connected to the power supply wiring 140 of the second radiating element 122. The RFIC 110 selectively transmits a high-frequency signal corresponding to the resonant frequency of the first radiating element 121 and a high-frequency signal corresponding to the resonant frequency of the third radiating element 123 to the diplexer 135. Here, the high-frequency signal corresponding to the resonant frequency of the first radiating element 121 is a low-band signal, and the high-frequency signal corresponding to the resonant frequency of the third radiating element 123 is a high-band signal.

[0099] The diplexer 135 includes a filter circuit that passes a high frequency signal corresponding to the resonant frequency of the first radiating element 121 and a filter circuit that passes a high frequency signal corresponding to the resonant frequency of the third radiating element 123 .

[0100] When a high-frequency signal corresponding to the resonant frequency of the first radiating element 121 is supplied from the RFIC 110 to the feed point SP2 via the diplexer 135, radio waves in the first frequency band are radiated from the second radiating element 122. When a high-frequency signal corresponding to the resonant frequency of the third radiating element 123 is supplied from the RFIC 110 to the feed point SP2 via the diplexer 135, radio waves in the second frequency band are radiated from the second radiating element 122. Note that, although the above embodiment has been described taking as an example a single-feed type in which a low-band signal and a high-band signal are supplied to the feed point SP2 via the diplexer 135, if a dual-feed type is adopted in which a low-band signal and a high-band signal are respectively fed to the second radiating element 122, the diplexer 135 is not necessary.

[0101] As described above, the antenna module 100B can emit radio waves in two different frequency bands. The antenna module 100B according to the third embodiment is applied to the communication device 10 in the same manner as the antenna module 100 according to the first embodiment. In the third embodiment, the first radiating element 121 emits radio waves in a first frequency band (e.g., 28 GHz), and the third radiating element 123 emits radio waves in a second frequency band (e.g., 39 GHz) higher than the first frequency band (e.g., 28 GHz). The first radiating element 121 is disposed on a layer between the third radiating element 123 and the ground electrode GND1. The antenna module 100B includes an RFIC 110 that feeds power to the third radiating element 123. The RFIC 110 is an example of a power feed circuit.

[0102] (Modifications) In each embodiment, the planar inverted-F antenna 190 is shown as an example of an inverted-F antenna provided in the antenna module. Instead of the planar inverted-F antenna, a rod-shaped inverted-F antenna may be used. In other words, the second radiating element 122 may be a rod-shaped element instead of a flat plate-shaped element.

[0103] An octagonal element is shown as an example of the first radiating element 121, and a circular element is shown as an example of the third radiating element 123. However, the first radiating element 121 and the third radiating element 123 may have any shape as long as they are plate-shaped.

[0104] A trapezoidal electrode is shown as an example of the peripheral electrode 150. However, the peripheral electrode 150 may have any shape, such as a rectangle or a circle.

[0105] In the third embodiment, an example has been shown in which the first radiating element 121 is a parasitic element and the third radiating element 123 is a fed element. However, the first radiating element 121 may be configured as a fed element and the third radiating element 123 may be configured as a parasitic element. Alternatively, the first radiating element 121 and the third radiating element 123 may be configured as fed elements.

[0106] [Aspects] It will be understood by those skilled in the art that the above-described embodiments are specific examples of the following aspects.

[0107] (Item 1) An antenna device according to one aspect includes a rectangular dielectric substrate formed by stacking a plurality of dielectric layers and having two pairs of opposing sides, at least one first radiating element formed on the dielectric substrate, at least one second radiating element arranged alongside the at least one first radiating element in a first direction that is orthogonal to the stacking direction of the dielectric substrate and parallel to one of the two pairs of opposing sides, a ground electrode arranged opposite the at least one first radiating element and the at least one second radiating element, and at least one peripheral electrode formed on a plurality of layers between the at least one first radiating element and the ground electrode and electrically connected to the ground electrode and the at least one second radiating element, and when the dielectric substrate is viewed in a plane from the stacking direction, of both end portions of the at least one second radiating element in a second direction that is orthogonal to the stacking direction and the first direction, the first end portion closer to a midline that divides the dielectric substrate into two equal parts in the first direction is an open end.

[0108] (Item 2) An antenna device according to item 1, wherein the at least one first radiating element includes two first radiating elements arranged side by side in a first direction, and the at least one second radiating element is arranged between the two first radiating elements.

[0109] (Clause 3) An antenna device according to clause 1 or clause 2, wherein when the dielectric substrate is viewed in a plan view from the stacking direction, at least one peripheral electrode includes two peripheral electrodes arranged to face each other in the second direction, and at least one second radiating element is arranged on each of the two peripheral electrodes.

[0110] (4) In the antenna device according to the first or second aspect, at least one second radiating element is connected to at least one peripheral electrode at a second end opposite to the first end.

[0111] (Clause 5) The antenna device of any one of clauses 1 to 4, wherein at least one first radiating element radiates radio waves in a first frequency band, and the antenna device further comprises a third radiating element provided for each of the at least one first radiating element and radiating radio waves in a second frequency band higher than the first frequency band, and a power feed circuit electrically connected to the third radiating element, wherein the at least one first radiating element is disposed on a layer between the corresponding third radiating element and the ground electrode, and the power feed circuit selectively outputs a first high-frequency signal corresponding to the first frequency band and a second high-frequency signal corresponding to the second frequency band.

[0112] (Item 6) An antenna module according to one aspect includes the antenna device of any one of items 1 to 5 and a power supply circuit.

[0113] (Clause 7) A communication device according to one aspect is equipped with the antenna module of clause 6. The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is indicated by the claims rather than the description of the above embodiments, and is intended to include all modifications within the meaning and scope of the claims.

[0114] 10 Communication device, 100, 100A, 100B Antenna module, 110 RFIC, 111A to 111D, 113A to 113D, 117 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, 118 Mixer, 119 Amplifier circuit, 120 Antenna device, 121 First radiating element, 122 Second radiating element, 122a First end, 122b Second end, 123 Third radiating element, 130 Dielectric substrate, 131 Upper surface, 132 Lower surface, 140, 141 Power supply wiring, 150 Peripheral electrode, 151, 181 Via, 160 Solder bump, 170 wiring pattern, 180 feeding electrode, 190 planar inverted-F antenna, 200 BBIC, 1000 SiP module, 1010 power module IC, 1020 power inductor, CP plane center, GND1, GND2 ground electrodes, SP1, SP2, SP4 feeding points, SP3 short-circuit point.

Claims

1. An antenna device comprising: a rectangular dielectric substrate formed by stacking a plurality of dielectric layers and having two pairs of opposing sides; at least one first radiating element formed on the dielectric substrate; at least one second radiating element arranged alongside the at least one first radiating element in a first direction that is orthogonal to the stacking direction of the dielectric substrate and parallel to one of the two pairs of opposing sides; a ground electrode arranged opposite the at least one first radiating element and the at least one second radiating element; and at least one peripheral electrode formed on a plurality of layers between the at least one first radiating element and the ground electrode and electrically connected to the ground electrode and the at least one second radiating element; when the dielectric substrate is viewed in a plane from the stacking direction, of both end portions of the at least one second radiating element in a second direction orthogonal to the stacking direction and the first direction, a first end portion closer to a midline that divides the dielectric substrate into two equal parts in the first direction is an open end.

2. The antenna device according to claim 1, wherein the at least one first radiating element includes two first radiating elements arranged side by side in the first direction, and the at least one second radiating element is arranged between the two first radiating elements.

3. An antenna device as described in claim 1 or claim 2, wherein, when the dielectric substrate is viewed in a plane from the stacking direction, the at least one peripheral electrode includes two peripheral electrodes arranged to face each other in the second direction, and the at least one second radiating element is arranged on each of the two peripheral electrodes.

4. The antenna device according to claim 1 or 2, wherein said at least one second radiating element is connected to said at least one peripheral electrode at a second end opposite said first end.

5. The antenna device according to any one of claims 1 to 4, wherein the at least one first radiating element radiates radio waves in a first frequency band, the antenna device further comprises: a third radiating element provided for each of the at least one first radiating element and radiating radio waves in a second frequency band higher than the first frequency band; and a power supply circuit electrically connected to the third radiating element, the at least one first radiating element being disposed in a layer between the corresponding third radiating element and the ground electrode, and the power supply circuit selectively outputs a first high-frequency signal corresponding to the first frequency band and a second high-frequency signal corresponding to the second frequency band.

6. An antenna module comprising the antenna device according to any one of claims 1 to 4 and a power supply circuit.

7. A communication device equipped with the antenna module according to claim 6.

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