Patent Application
20230327338
The present disclosure relates to antenna modules and communication devices equipped with the antenna modules, and more specifically relates to a technique for expanding the area of radiation of a radio wave in an antenna module.
Japanese Patent No. 6384550 (Patent Document 1) describes a wireless communication module in which an end-fire antenna (dipole antenna) and a plate-like patch antenna are arranged on the same substrate. With the foregoing configuration, the dipole antenna and the patch antenna can be operated as an array antenna by setting the polarization direction of a radio wave emitted from the dipole antenna and the polarization direction of a radio wave emitted from the patch antenna in the same direction. Accordingly, the directivity can vary continuously from the end-fire direction (direction parallel to a surface of the substrate) to the boresight direction (direction vertical to the substrate).
In the wireless communication module described in Japanese patent No. 6384550 (Patent Document 1), a reflector pattern is disposed in between the dipole antenna and the patch antenna, and the dipole antenna thus emits a radio wave approximately in the opposite direction to the patch antenna. However, in general, the beam direction of a radio wave emitted from the dipole antenna spreads out widely. Thus, with the configuration disclosed in Japanese patent No. 6384550 (Patent Document 1), part of the radio wave emitted from the dipole antenna is emitted across a wide area ranging from the end-fire direction to the boresight direction. Accordingly, the area of radiation caused by the dipole antenna partially overlaps the area of radiation caused by the patch antenna. In the dipole antenna, because of this radiation of a radio wave to the overlapping area, power being used for radiation in the end-fire direction may be limited. Therefore, there is room for improvement regarding efficiency of a radio wave being emitted from the dipole antenna in the end-fire direction.
The present disclosure, among other inventive aspects, resolves the foregoing issues by, for example, improving the efficiency of a radio wave being emitted in the end-fire direction in an antenna module in which a plurality of radiating elements including a linear antenna are disposed.
An antenna module according to the present disclosure includes a dielectric substrate, a first radiating element and a second radiating element disposed in or on the dielectric substrate, and a first dielectric layer. The second radiating element is disposed next to the first radiating element in a plan view seen from a direction normal to the dielectric substrate. The first dielectric layer is disposed to cover the second radiating element. The second radiating element is a linear antenna. A dielectric constant of the first dielectric layer is higher than a dielectric constant of the dielectric substrate. A thickness of the first dielectric layer is smaller than a thickness of the dielectric substrate.
According to the antenna module of the present disclosure, the second radiating element which is a linear antenna is covered by the dielectric layer that has a thickness smaller than a thickness of the dielectric substrate and is made of a material whose dielectric constant is higher than a dielectric constant of the dielectric substrate. According to the foregoing configuration, the second radiating element is more likely to emit a radio wave in the end-fire direction than in the boresight direction. Therefore, it becomes possible to improve the efficiency of a radio wave being emitted in the end-fire direction.
Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the same reference characters are assigned to the same or corresponding parts in the drawings, and the descriptions thereof will not be repeated.
(Basic Configuration of Communication Device)
Referring to
In the antenna device 120 of
In the antenna module 100 of exemplary Embodiment 1, the radiating element 121 is a planar antenna such as a patch antenna or a slot antenna. On the other hand, the radiating element 122 is a linear antenna such as a monopole antenna, a dipole antenna, an inverted-F antenna, or a bowtie antenna. In the example of
For ease of description,
The RFIC 110 includes switches 111A to 111H, 113A to 113H, 117A, and 117B, power amplifiers 112AT to 112HT, low-noise amplifiers 112AR to 112HR, attenuators 114A to 114H, phase shifters 115A to 115H, signal combiner/splitters 116A and 116B, mixers 118A and 118B, and amplifier circuits 119A and 119B. Of these constituent elements, the configuration including the switches 111A to 111D, 113A to 113D, and 117A, the power amplifiers 112AT to 112DT, the low-noise amplifiers 112AR to 112DR, the attenuators 114A to 114D, the phase shifters 115A to 115D, the signal combiner/splitter 116A, the mixer 118A, and the amplifier circuit 119A is circuitry for the radiating element 121. Further, the configuration including the switches 111E to 111H, 113E to 113H, and 117B, the power amplifiers 112ET to 112HT, the low-noise amplifiers 112ER to 112HR, the attenuators 114E to 114H, the phase shifters 115E to 115H, the signal combiner/splitter 116B, the mixer 118B, and the amplifier circuit 119B is circuitry for the radiating element 122.
In a case that a radio frequency signal is to be transmitted, the switches 111A to 111H and 113A to 113H are switched to the sides of the power amplifiers 112AT to 112HT, and the switches 117A and 117B are connected to transmitting side amplifiers of the amplifier circuits 119A and 119B. In a case that a radio frequency signal is to be received, the switches 111A to 111H and 113A to 113H are switched to the sides of the low-noise amplifiers 112AR to 112HR, and the switches 117A and 117B are connected to receiving side amplifiers of the amplifier circuits 119A and 119B.
Signals transferred from the BBIC 200 are amplified in the amplifier circuits 119A and 119B and up-converted in the mixers 118A and 118B. Transmitting signals that are up-converted radio frequency signals are each split into four signals in the signal combiner/splitters 116A and 116B, and these split signals are fed to different radiating elements 121 and 122 after traveling through corresponding signal paths. The directivity of the antenna device 120 can be adjusted by individually adjusting the degree of phase shift in the phase shifters 115A to 115H that are disposed in the respective signal paths.
Received signals that are radio frequency signals received by the respective radiating elements 121 and 122 are transferred to the RFIC 110 and combined in the signal combiner/splitters 116A and 116B after traveling through the four different signal paths. Combined received signals are down-converted in the mixers 118A and 118B, amplified in the amplifier circuits 119A and 119B, and transferred to the BBIC 200.
The RFIC 110 is formed as, for example, a one-chip integrated circuit component including the circuit configuration described above. Alternatively, devices (switches, power amplifiers, low-noise amplifiers, attenuators, and phase shifters) in the RFIC 110 corresponding to each radiating element may be formed as a one-chip integrated circuit component for each radiating element.
(Configuration of Antenna Module)
Next, referring to
Referring to
The dielectric substrate 130 is, for example, a low temperature co-fired ceramics (LTCC) multilayer substrate, a multilayer resin substrate in which resin layers, each of which is made of a resin such as epoxy, polyimide, or the like, are laminated, a multilayer resin substrate in which resin layers, each of which is made of a liquid crystal polymer (LCP) having a lower dielectric constant, are laminated, a multilayer resin substrate in which resin layers, each of which is made of a fluorine-based resin, are laminated, or a ceramics multilayer substrate other than LTCC. Note that the dielectric substrate 130 does not necessarily have a multilayer structure and may alternatively be a single layer substrate.
In plan view seen from the direction normal to the dielectric substrate 130 (Z-axis direction), the dielectric substrate 130 has a substantially rectangular shape. On a top surface 131 (surface in the positive direction of the Z-axis) side of the dielectric substrate 130, the radiating element 121 is disposed. The radiating element 121 may be configured to be exposed to the surface of the dielectric substrate 130 or may be disposed in an internal layer of the dielectric substrate 130. Further, the ground electrode GND is disposed on a bottom surface 132 (surface in the negative direction of the Z-axis) of the dielectric substrate 130 or in an internal layer on the bottom surface 132 side as illustrated in
The radiating element 122 is disposed next to the radiating element 121 on the top surface 131 of the dielectric substrate 130. In the example of
The RFIC 110 is mounted on the bottom surface 132 of the dielectric substrate 130 with solder bumps 150 interposed therebetween. Note that the RFIC 110 may be connected to the dielectric substrate 130 using, instead of the solder connection, a multipole connector.
A radio frequency signal is transferred to the radiating element 121 from the RFIC 110 via a feed line 141. The feed line 141 passes through the ground electrode GND from the RFIC 110 and is connected to a feed point SP1 from the bottom surface side of the radiating element 121. That is to say, the feed line 141 transfers a radio frequency signal to the feed point SP1 of the radiating element 121. The feed point SP1 is provided at a location that is shifted from the center of the radiating element 121 in the positive direction of the Y-axis. By supplying a radio frequency signal to the feed point SP1, a radio wave whose polarization direction is the Y-axis direction is emitted from the radiating element 121.
A radio frequency signal is transferred to the radiating element 122 from the RFIC 110 via a feed line 142. The feed line 142 passes through the ground electrode GND from the RFIC 110 and is connected to a feed point SP2 of the radiating element 122. By supplying a radio frequency signal to the feed point SP2, a radio wave whose polarization direction is the Y-axis direction is emitted from the radiating element 122.
The dielectric layer 135 is disposed on the top surface 131 of the dielectric substrate 130 and covers the radiating element 122. The dielectric layer 135 is made of, for example, glass or ceramic and is made of a material that has a higher dielectric constant than a dielectric constant of the dielectric substrate 130. For example, the dielectric constant of the dielectric layer 135 is 6 to 30, and the dielectric constant of the dielectric substrate 130 is 3 to 4. Further, a thickness (dimension in the Z-axis direction) H2 of the dielectric layer 135 is smaller than a thickness H1 of the dielectric substrate 130 (H1>H2).
With a flat plate shape patch antenna such as the radiating element 121, basically, a radio wave is emitted in the direction (arrow AR11 in
However, with a linear antenna such as a dipole antenna, a radio wave spreads across a wide range in a case that the radio wave is emitted, and thus the intensity of the radio wave emitted in each direction becomes weaker relative to the power being supplied. Further, as in the case with the antenna module 100 according to Embodiment 1, in a case that the radiating element 121 which is a patch antenna is used together with the radiating element 122, the radiating element 122 also emits a radio wave in a direction that overlaps the direction of a radio wave being emitted from the radiating element 121. Accordingly, in the configuration in which a patch antenna that mostly emits a radio wave in the boresight direction and a dipole antenna that emits in all directions are simply disposed side by side, there is room for improvement regarding the efficiency of the radio wave in the end-fire direction.
In the antenna module 100 of Embodiment 1, the radiating element 122 is covered by the dielectric layer 135 that has a smaller thickness and a higher dielectric constant than the dielectric substrate 130. With the foregoing configuration, the dielectric layer 135 functions as a waveguide, and of a radio wave being emitted from the radiating element 122, the mode of a radio wave being emitted in the boresight direction is suppressed. As a result, the intensity of a radio wave being emitted in the end-fire direction increases. In other words, a beam of the radio wave being emitted from the radiating element 122 can be concentrated in the end-fire direction. Therefore, it becomes possible to improve the efficiency of the radio wave being emitted in the end-fire direction.
Further, the inventor has found that a radio wave is likely to be emitted in a direction opposite to the radiating element 121 (that is, the negative direction of the X-axis) by making a distance W1 (first distance) from the radiating element 122 to the edge of the dielectric substrate 130 in a direction (first direction) from the center of the radiating element 121 to the center of the radiating element 122 longer than a distance W2 (second distance) from the radiating element 122 to the edge of the dielectric layer 135 in a direction (second direction) from the center of the radiating element 122 to the center of the radiating element 121. By setting the spatial relationship between the radiating element 122 and the dielectric layer 135 as described above, a beam of a radio wave emitted from the radiating element 122 can be concentrated in an outward direction from the antenna module 100, and thus it becomes possible to further improve the efficiency of the radio wave being emitted in the end-fire direction. Note that the center of the radiating element 122 which is a dipole antenna refers to the location at the center in an extending direction of an electrode. In other words, in
Note that although it is not illustrated in the drawings, the beam from the radiating element 122 may be concentrated in the outward direction from the antenna module 100 by providing a reflector for the radiating element 122 in between the radiating element 121 and the radiating element 122.
As described above, the antenna module 100 of Embodiment 1 has the configuration in which the radiating element 121 which is a patch antenna and the radiating element 122 which is a dipole antenna are disposed next to each other on the dielectric substrate 130 and the radiating element 122 is covered by the dielectric layer 135 that is made of a material having a smaller thickness and a higher dielectric constant than the dielectric substrate 130. With the foregoing configuration, the radiating element 122 is more likely to emit a radio wave in the end-fire direction than in the boresight direction. Therefore, in the antenna module 100 of exemplary Embodiment 1, it becomes possible to improve the efficiency of a radio wave being emitted in the end-fire direction.
Regarding the antenna module 100 of exemplary Embodiment 1, the configuration is described in which the ground electrode GND is disposed over substantially the whole area of the dielectric substrate 130 in plan view of the dielectric substrate 130 seen from the direction normal to the dielectric substrate 130.
However, if the ground electrode GND is disposed on the bottom surface side of the radiating element 122 which is a dipole antenna, the radiating element 122 couples with the ground electrode GND, and part of a current flows from the radiating element 122 to the ground electrode GND side. In some cases, this narrows the frequency band width of a radio wave being emitted from the radiating element 122.
In an antenna device 120A included in an antenna module 100A of Modification 1 illustrated in
In the antenna modules of exemplary Embodiment 1 and Modification 1, the dielectric layer 135 is disposed on the top surface 131 of the dielectric substrate 130, and there is a level difference between the portion having the dielectric layer 135 and the portion not having the dielectric layer 135. In a process of mounting an antenna module on a mounting substrate or the like, the antenna module may be picked up by suction using a nozzle. In this case, as described above, if there is a level difference on a surface of a component, air may leak from a level difference part, and it may be difficult to properly pick up the antenna module.
In an antenna device 120B included in an antenna module 100B of Modification 2 illustrated in
As described above, by planarizing the surface of the antenna module by reducing the level difference, it becomes possible to improve reliability of antenna module handling in a fabrication process of the antenna module.
In exemplary Embodiment 1 and Modifications 1 and 2 described above, the configuration is described in which the dipole antenna (radiating element 122) is disposed on the top surface 131 of the dielectric substrate 130 and the dielectric layer 135 is disposed to cover the radiating element 122. However, the radiating element 122 is not necessarily disposed on the top surface 131 of the dielectric substrate 130.
For example, as in the cases of antenna modules 100C to 100F according to Modification 3 to Modification 6 illustrated in
Each of the antenna modules of the Modifications 3 to 6 also has the configuration in which the radiating element 122 is covered by the dielectric layer 135 that is made of a material having a smaller thickness and a higher dielectric constant than the dielectric substrate 130. Because of this, it becomes possible to improve the efficiency of a radio wave being emitted in the end-fire direction.
In exemplary Embodiment 1 and Modifications thereof, the configuration is described using the example in which one radiating element 121 and one radiating element 122 of the antenna module are disposed. In exemplary Embodiment 2, a case of an array antenna in which a plurality of radiating elements 121 and a plurality of radiating elements 122 are disposed is described.
Because of the arrangement of the dielectric layer 135 having a higher dielectric constant, also in an array antenna such as the antenna module 100G, the radiating elements 122 of the antenna group 126 are more likely to emit radio waves in the end-fire direction than in the boresight direction. Therefore, it becomes possible to improve the efficiency of a radio wave being emitted in the end-fire direction.
In Modification 7, an array antenna whose configuration enables radio wave radiation in two different directions using linear antennas is described.
The radiating elements 122A of the antenna group 127 are disposed to face the opposite direction of the radiating elements 122 of the antenna group 126. Accordingly, the radiating elements 122A of the antenna group 127 emit radio waves in the direction opposite to the radiating elements 122. Specifically, the radiating elements 122 emit a radio wave in the negative direction of the X-axis (arrow AR21 in
Furthermore, the radiating elements 122A are also covered by the dielectric layer 135 that has a smaller thickness and a higher dielectric constant than the dielectric substrate 130.
As described above, also in the array antenna including the two antenna groups 126 and 127 that emit radio waves in two end-fire directions that are different from each other, the radio waves are more likely to be emitted in the end-fire directions than in the boresight direction by covering these antenna groups 126 and 127 with the dielectric layer 135 having a higher dielectric constant. Therefore, it becomes possible to improve the efficiency of a radio wave being emitted in the end-fire directions.
Note that the example of
In Modification 8, an array antenna whose configuration enables radio wave radiation in four different directions using linear antennas is described.
In the radiating element 122B included in the antenna group 128, a linear electrode extends in the X-axis direction. Further, also in the radiating element 122C included in the antenna group 129, a linear electrode extends in the X-axis direction. Furthermore, the dielectric layer 135 is disposed to cover the antenna groups 128 and 129. The dielectric layer 135 and all the radiating elements included in the antenna groups 128 and 129 are disposed to have a spatial relationship similar to the spatial relationship illustrated in
Furthermore, as described above, because these antenna groups 128 and 129 are covered by the dielectric layer 135 having a higher dielectric constant and a smaller thickness than the dielectric substrate 130, radio waves being emitted from the antenna groups 128 and 129 are more likely to be emitted in the end-fire direction than in the boresight direction. Therefore, by using a configuration such as the antenna module 100I, it becomes possible to efficiently emit a radio wave in the end-fire directions in the Y-axis direction in addition to the end-fire directions in the X-axis direction.
Note that Modification 8 is described using the configuration in which the antenna groups 126 to 129 emit radio waves in four different end-fire directions. Alternatively, the configuration may include any three of the antenna groups 126 to 129 for emitting radio waves in three different end-fire directions.
Further, characteristic features described in Modification 1 and Modification 2 may be employed in Embodiment 2 and Modifications 7 and 8. Further, in the configurations of Modifications 7 and 8, the number of the radiating elements included in each antenna group may be one.
It is to be understood that the exemplary embodiments disclosed herein are exemplary in all aspects and are not restrictive. It is intended that the scope of the present disclosure is defined by the claims, not by the description of the exemplary embodiments, and includes all variations which come within the meaning and range of equivalency of the claims.
10 Communication device, 100, 100A to 1001 Antenna module, 110 RFIC, 111A to 111H, 113A to 113H, 117A, 117B Switch, 112AR to 112HR Low-noise amplifier, 112AT to 112HT Power amplifier, 114A to 114H Attenuator, 115A to 115H Phase shifter, 116A, 116B Signal combiner/splitter, 118A, 118B Mixer, 119A, 119B Amplifier circuit, 120, 120A to 1201 Antenna device, 121, 122, 122A to 122C Radiating element, 125 to 129 Antenna group, 130 Dielectric substrate, 130A, 135 Dielectric layer, 131, 131A, 135A Top surface, 132 Bottom surface, 141, 142 Feed line, 150 Solder bump, 200 BBIC, GND Ground electrode, SP1, SP2 Feed point
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-208336 | Dec 2020 | JP | national |
This application is a continuation of, and claims the benefit of priority to international patent application no. PCT/JP2021/042069, filed Nov. 16, 2021, and which claims priority to Japanese patent application no. 2020-208336, filed Dec. 16, 2020. The entire contents of all prior applications are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2021/042069 | Nov 2021 | US |
| Child | 18335181 | US |
