Patent Application
20240186723
The present disclosure relates to an antenna module and a communication device equipped therewith, and more specifically to technology for improving the antenna characteristics of an antenna module capable of emitting radio waves in two directions.
International Publication No. 2020/170722 (Patent Document 1) discloses an antenna module in which emitting elements are disposed on two surfaces of a dielectric substrate having a flat plate-like shape folded into a substantially L shape, the two surfaces having different normal directions. In the antenna module disclosed in Patent Document 1, radio waves can be emitted in different directions from the emitting elements on the respective surfaces of the dielectric substrate.
Antenna modules as described above may be used in mobile communication devices such as, typically, cellular phones or smartphones. In recent years, such mobile communication devices have been communicating using radio waves of a plurality of frequency bands corresponding to different communication standards. In this case, emitting elements corresponding to the individual frequency bands are disposed on the individual surfaces of the dielectric substrate.
In a case where the emitting elements corresponding to different frequency bands are disposed adjacent to each other on the individual surfaces of the dielectric substrate, the emitting elements need to be disposed in the limited space of the dielectric substrate, which may lead to a state where the emitting elements need to be disposed at a high density. Assuming this is the case, the emitting elements disposed on different surfaces of the dielectric substrate will be close to each other, and the isolation characteristics between these emitting elements may decrease.
The present disclosure has been made to solve such a problem, and a purpose of the present disclosure is to suppress deterioration of isolation characteristics between emitting elements disposed on the individual surfaces of the dielectric substrate in an antenna module capable of emitting radio waves in two different directions.
An antenna module according to the present disclosure includes a first substrate and a second substrate, whose normal directions are different from each other, a first emitting element and a second emitting element, which are disposed on the first substrate, and a third emitting element and a fourth emitting element, which are disposed on the second substrate. The first emitting element and the third emitting element are capable of emitting radio waves of a first frequency band. The second emitting element and the fourth emitting element are capable of emitting radio waves of a second frequency band higher than the first frequency band. The second emitting element is disposed adjacent to the first emitting element in a case where the first substrate is viewed in a plan view from the normal direction. On the first substrate, the first emitting element is disposed at a position that is farther from the second substrate than the second emitting element is.
With the antenna module according to the present disclosure, on the first substrate side, the emitting element for the lower frequency band is disposed at a position that is farther from the second substrate than the emitting element for the higher frequency band is. The wavelength of radio waves emitted from the emitting element for the lower frequency band is longer than that of radio waves emitted from the emitting element for the higher frequency band, and thus the emitting element for the lower frequency band is likely to have a greater effect on the emitting elements on the second substrate side. Therefore, by disposing the emitting element for the lower frequency band at a position that is relatively farther from the second substrate, the deterioration of isolation characteristics can be suppressed between the emitting elements on the first substrate side and the emitting elements on the second substrate side.
In the following, an embodiment of the present disclosure will be described in detail with reference to the drawings. Note that identical or equivalent portions in the drawings are marked with the same symbols and description thereof is not repeated.
With reference to
The antenna device 120 includes two dielectric substrates 130A and 130B. A plurality of emitting elements are disposed on each dielectric substrate. More specifically, in the example illustrated in
Each of the dielectric substrates 130A and 130B has a substantially rectangular shape. The plurality of electrodes of each of the emitting elements 121A and 122A are arranged in a row along the long side of the dielectric substrate 130A. The individual electrodes of the emitting elements 121B and 122B are arranged in a row along the long side of the dielectric substrate 130B.
In the present embodiment, each electrode of the emitting elements 121A, 122A, 121B, and 122B is a planar patch antenna having a substantially square shape. The electrode sizes of the emitting elements 121A and 121B (the lengths of the sides of the electrodes) are larger than those of the emitting elements 122A and 122B. Thus, the frequency bands of radio waves emitted from the individual electrodes of the emitting elements 121A and 121B are lower than those of radio waves emitted from the individual electrodes of the emitting elements 122A and 122B. That is, the antenna module 100 is a so-called dual-band antenna module capable of emitting radio waves of two different frequency bands. In the example in the present embodiment, the center frequency of radio waves emitted from the emitting elements 121A and 121B for the lower frequency band is 28 GHz, and the center frequency of radio waves emitted from the emitting elements 122A and 122B for the higher frequency band is 39 GHz.
To the emitting elements 121A and 121B for the lower frequency band, radio frequency signals are supplied from the RFIC 110A. In contrast, to the emitting elements 122A and 122B for the higher frequency band, radio frequency signals are supplied from the RFIC 110B.
With reference to
In a case where radio frequency signals are to be transmitted, the switches 111A to 111H and 113A to 113H are switched to the side where the power amplifiers 112AT to 112HT are provided, and also the switches 117A and 117B are connected to the transmission-side amplifiers of the amplification circuits 119A and 119B. In a case where radio frequency signals are to be received, the switches 111A to 111H and 113A to 113H are switched to the side where the low noise amplifiers 112AR to 112HR are provided, and also the switches 117A and 117B are connected to the reception-side amplifiers of the amplification circuits 119A and 119B.
Signals transmitted from the BBIC 200 are amplified by the amplification circuits 119A and 119B and are then up-converted by the mixers 118A and 118B. Transmission signals that are up-converted radio frequency signals are separated into four signals by the signal multiplexing/demultiplexing devices 116A and 116B, and the four signals pass through the corresponding signal paths and are fed to the emitting elements 121A and 121B. In this case, by separately adjusting the degrees of phase shift of the phase shifters 115A to 115H disposed in the respective signal paths, the directivity of the antenna device 120 can be adjusted. Moreover, the attenuators 114A to 114H adjust the strengths of transmission signals.
Reception signals, which are radio frequency signals received by the respective emitting elements 121A and 121B, are transmitted to the RFIC 110A, travel along the respective different signal paths, and are multiplexed by the signal multiplexing/demultiplexing devices 116A and 116B. The multiplexed reception signals are down-converted by the mixers 118A and 118B and are furthermore amplified by the amplification circuits 119A and 119B, and the resulting signals are transmitted to the BBIC 200.
The RFIC 110A is, for example, formed as a one-chip integrated circuit component including the above-described circuit configuration. Alternatively, the devices (the switches, the power amplifiers, the low noise amplifiers, the attenuators, the phase shifters) corresponding to the individual emitting elements 121A and 121B in the RFIC 110A may be formed as a one-chip integrated circuit component for each corresponding emitting element.
Note that
Note that the “dielectric substrate 130A and dielectric substrate 130B” in the present embodiment correspond to a “first substrate” and a “second substrate” according to the present disclosure, respectively. The “emitting element 121A”, the “emitting element 122A”, the “emitting element 121B”, and the “emitting element 122B” according to the embodiment correspond to a “first emitting element”, a “second emitting element”, a “third emitting element”, and a “fourth emitting element” according to the present disclosure, respectively.
Next, with reference to
The antenna module 100 includes the dielectric substrates 130A and 130B as described above, and is disposed on a mounting substrate 50, which is a substantially rectangular parallelepiped. Note that, in the following description, the normal direction of a main surface 51 of the mounting substrate 50 is the Z-axis, and the directions along two sides of the main surface 51 are the X-axis and Y-axis directions.
The dielectric substrates 130A and 130B are, for example, low temperature co-fired ceramic (LTCC) multilayer substrates, multilayer resin substrates formed by laminating a plurality of resin layers consisting of epoxy, polyimide, and other resins, multilayer resin substrates formed by laminating a plurality of resin layers consisting of liquid crystal polymers (LCPs) having lower dielectric constants, multilayer resin substrates formed by laminating a plurality of resin layers consisting of fluorine-based resins, or multilayer ceramic substrates other than LTCC multilayer substrates. Note that the dielectric substrates 130A and 130B do not have to have multilayer structures and may be single-layer substrates.
Each of the dielectric substrates 130A and 130B has a flat plate-like shape extending schematically in the X-axis direction. The dielectric substrate 130A and the dielectric substrate 130B are disposed such that their normal directions are different from each other. Specifically, the dielectric substrate 130A is disposed such that its normal direction matches the Z-axis direction, and the dielectric substrate 130B is disposed such that its normal direction matches the Y-axis direction. In other words, the dielectric substrate 130A is disposed so as to face the main surface 51 of the mounting substrate 50, and the dielectric substrate 130B is disposed so as to face a side surface 52 of the mounting substrate 50 along the X-axis. The RFIC 110 is disposed between the dielectric substrate 130A and the mounting substrate 50. Note that the normal direction of the dielectric substrate 130A and the normal direction of the dielectric substrate 130B do not have to be orthogonal to each other. For example, the angle formed between the two normal directions may range from 80° to 100°.
The dielectric substrate 130A and the dielectric substrate 130B are connected to each other by connection members 135. In the antenna module 100, the dielectric substrates 130A and 130B are almost equal in length in the X-axis direction, and the connection members 135 are formed at least both end portions of each dielectric substrate. Note that a connection member 135 may also be formed at middle portions of the dielectric substrates in the X-axis direction. Dielectric substrate torsion can be suppressed by connecting the end portions of the dielectric substrates to each other. When viewed in a plan view from the X-axis direction, the antenna device 120 is formed in a substantially L shape by the dielectric substrates 130A and 130B and the connection members 135.
A ground electrode GND is disposed over the entire surface of the side (back side) of the dielectric substrate A that faces the mounting substrate 50. The ground electrode GND extends from the dielectric substrate 130A through the connection members 135 to the dielectric substrate 130B.
The dielectric substrate 130A has a substantially rectangular shape when viewed in a plan view from its normal direction (the Z-axis direction). On the dielectric substrate 130A, three electrodes of the emitting element 121A are disposed along the X-axis direction. Moreover, on the dielectric substrate 130A, three electrodes of the emitting element 122A are disposed along the X-axis direction. The electrodes of the emitting element 121A and the electrodes of the emitting element 122A are disposed adjacent to each other along the X-axis direction in an alternating manner. Note that, in
Each electrode of the emitting element 121A is arranged diagonally so that each side of the electrode forms 450 with respect to the X-axis direction. Each electrode of the emitting element 121A is disposed at the position where the distance from the end surface of the dielectric substrate 130A on the dielectric substrate 130B side to the center of the electrode of the emitting element 121A is L1.
Similarly, each electrode of the emitting element 122A is disposed diagonally so that each side of the electrode forms 45° with respect to the X-axis direction. Each electrode of the emitting element 122A is disposed at the position where the distance from the end surface of the dielectric substrate 130A on the dielectric substrate 130B side to the center of the electrode of the emitting element 122A is L2.
In this case, the distance L1 from the end portion of the dielectric substrate 130A is longer than the distance L2. That is, the emitting element 121A is disposed at a position that is farther from the dielectric substrate 130B than the emitting element 122A is.
In each electrode of the emitting elements 121A and 122A, radio frequency signals are supplied from the RFIC 110 to two power supply points. The power supply points of each electrode are positioned at 450 with respect to the direction parallel to the X-axis through the center of the electrode, and at 45° with respect to the direction parallel to the Y-axis through the center of the electrode. As a result, radio waves with a polarization direction at 45° with respect to the X-axis direction and radio waves with a polarization direction at 45° with respect to the Y-axis direction are emitted from each electrode of the emitting elements 121A and 122A.
When viewed in a plan view from the normal direction (the Y-axis direction), the dielectric substrate 130B has a substantially rectangular shape with notches formed at portions corresponding to the connection members 135. The dielectric substrate 130B has a protrusion 136 formed at the portion where the above-described notches are not formed, the protrusion 136 protruding in the Z-axis direction. In the region of the protrusion 136 of the dielectric substrate 130B, two electrodes of the emitting element 121B and two electrodes of the emitting element 122B are disposed along the X-axis direction. The electrodes of the emitting elements 121B and the electrodes of the emitting elements 122B are disposed along the X-axis direction in an alternating manner. Note that, in
Note that, although not illustrated in the drawing, radio frequency signals are supplied from the RFIC 110 to the emitting elements 121B and 122B through power feed lines that extend from the dielectric substrate 130A through the connection members 135 to the dielectric substrate 130B.
Each electrode of the emitting element 122B is arranged diagonally so that each side of the electrode is at 450 with respect to the X-axis direction. In each electrode of the emitting element 122B, radio frequency signals from the RFIC 110 are supplied to the two power supply points. The power supply points of each electrode of the emitting element 122B are positioned at 45° with respect to the direction parallel to the X-axis through the center of the electrode, and at 450 with respect to the direction parallel to the Z-axis through the center of the electrode. As a result, radio waves with a polarization direction at 450 with respect to the X-axis direction and radio waves with polarization at 450 with respect to the Z-axis direction are emitted from each electrode of the emitting element 122B.
In contrast, when viewed in a plan view from the normal direction (the Y-axis direction) of the dielectric substrate 130B, each electrode of the emitting element 121B has a substantially octagonal shape. This is because the size of the dielectric substrate 130B in the Z-axis direction is limited, and thus similarly to the emitting element 122B, the electrode is arranged at a 450 tilt in a state where four corners of the electrode, which has a square shape, are cut out. Even regarding each electrode of the emitting element 121B, the power supply points are positioned at 450 with respect to the direction parallel to the X-axis through the center of the electrode, and at 450 with respect to the direction parallel to the Z-axis through the center of the electrode. As a result, radio waves with a polarization direction at 450 with respect to the X-axis direction and radio waves with a polarization direction at 450 with respect to the Z-axis direction are emitted also from each electrode of the emitting element 121B.
Note that in a case where an end surface of the dielectric substrate 130A that is close to the dielectric substrate 130B is a first end surface, and an end surface of the dielectric substrate 130B that is close to the dielectric substrate 130A is a second end surface, assuming the dielectric substrate 130A is viewed in a plan view from its normal direction, a direction (a first direction) along the first end surface is the X-axis direction, and a direction (second direction) orthogonal to the direction along the first end surface is the Y-axis direction. Moreover, assuming the dielectric substrate 130B is viewed in a plan view from its normal direction, a direction (a third direction) along the second end surface is the X-axis direction, and a direction (a fourth direction) orthogonal to the direction along the second end surface is the Z-axis direction.
In an antenna module having a configuration as described above, in a case where the size of the dielectric substrate 130A in the Y-axis direction is limited, the emitting elements 121A and 122A of the dielectric substrate 130A are disposed so as to be close to the emitting elements 121B and 122B disposed on the dielectric substrate 130B. Basically, the direction of emission of radio waves from the emitting elements 121A and 122A is the positive direction of the Z-axis, and the direction of emission of radio waves from the emitting elements 121B and 122B is the negative direction of the Y-axis. However, assuming the emitting elements on the dielectric substrate 130A side are close to the emitting elements on the dielectric substrate 130B side, lines of electric force generated from the electrodes partially overlap and interfere with each other, and the isolation between the emitting elements of the dielectric substrate 130A and the emitting elements on the dielectric substrate 130B side may decrease.
In particular, in a dual-band antenna module such as the antenna module 100 according to the embodiment, the isolation is likely to decrease for radio waves in the lower frequency band, which have relatively longer electrical lengths, than for radio waves in the higher frequency band. This is because radio waves in the lower frequency band appear electrically closer due to the longer wavelength even at the same distance and because the emitting element for the lower frequency band is more likely to couple with the emitting elements on the dielectric substrate 130B side due to the electrode sizes of the emitting elements being larger than those of the electrodes for the higher frequency band.
In the antenna module 100 according to the present embodiment, the emitting element 121A of the dielectric substrate 130A for the lower frequency band is disposed at a position that is farther from the dielectric substrate 130B than the emitting element 122A for the higher frequency band is. In this manner, the deterioration of isolation characteristics can be suppressed by disposing, away from the dielectric substrate 130B, the emitting element 121A for the lower frequency band that has a greater effect on the deterioration of isolation.
Next, the isolation characteristics of the antenna module 100 according to the embodiment will be described using a comparative example.
As described above, in a dual-band antenna module capable of emitting radio waves in two different directions, the deterioration of isolation can be suppressed by disposing emitting elements on one dielectric substrate such that an emitting element for the lower frequency band is disposed at a position that is farther from the other dielectric substrate than an emitting element for the higher frequency band is.
Note that, in the antenna module 100 according to the embodiment, the configuration has been described in which the emitting elements 121B and 122B are separately disposed on the dielectric substrate 130B; however, the antenna module 100 according to the embodiment may have a stacking structure in which the electrodes of the emitting element 121B and the electrodes of the emitting element 122B are stacked in the normal direction (the Y-axis direction).
Moreover, in the antenna module 100, the polarization direction of radio waves emitted from each electrode of the emitting elements is tilted at 45° with respect to the coordinate axis in the drawing (for example, the X-axis); however, the tilt of the polarization direction is not limited to this and may be any angle greater than 0° and smaller than 90°.
In the following, the configurations of antenna modules according to modifications will be described using
In the antenna module 100 according to the embodiment, the case of the antenna array has been described in which each emitting element includes a plurality of electrodes. In a first modification, a case will be described in which each emitting element includes one electrode.
In this manner, even in an antenna module including the emitting elements, each of which is constituted by a single electrode, the deterioration of isolation can be suppressed by disposing an emitting element for the lower frequency band at a position that is farther from the other dielectric substrate than an emitting element for the higher frequency band is.
In a second modification, a configuration will be described in which the polarization directions of the emitting elements on the dielectric substrate 130A side are made different.
With reference to
On each of the electrodes of the emitting elements 121A1 and 122A1, power supply points are disposed at a position offset from the center of the electrode in the positive direction of the X-axis and a position offset from the center of the electrode in the positive direction of the Y-axis. That is, from the individual electrodes, radio waves whose polarization direction is the X-axis direction and radio waves whose polarization direction is the Y-axis direction are emitted.
Even in the antenna module 100B, the emitting element 121A1 of the dielectric substrate 130A for the lower frequency band is disposed at a position that is farther from the dielectric substrate 130B than the emitting element 122A1 for the higher frequency band is. Thus, the deterioration of isolation can be suppressed even in the antenna module 100B.
In a third modification, a configuration will be described in which the polarization directions of the emitting elements on the dielectric substrate 130B side are made different.
With reference to
On each of the electrodes of the emitting elements 121B1 and 122B1, power supply points are disposed at a position offset from the center of the electrode in the positive direction of the X-axis and a position offset from the center of the electrode in the positive direction of the Z-axis. That is, from the individual electrodes, radio waves whose polarization direction is the X-axis direction and radio waves whose polarization direction is the Z-axis direction are emitted.
Even in the antenna module 100C, the emitting element 121A of the dielectric substrate 130A for the lower frequency band is disposed at a position that is farther from the dielectric substrate 130B than the emitting element 122A for the higher frequency band is. Thus, the deterioration of isolation can be suppressed even in the antenna module 100C.
In a fourth modification, a configuration will be described in which the polarization directions of the emitting elements on both the dielectric substrate 130A side and the dielectric substrate 130B side are made different.
With reference to
On each of the electrodes of the emitting elements 121A1 and 122A1, power supply points are disposed at a position offset from the center of the electrode in the positive direction of the X-axis and a position offset from the center of the electrode in the positive direction of the Y-axis. That is, from the individual electrodes, radio waves whose polarization direction is the X-axis direction and radio waves whose polarization direction is the Y-axis direction are emitted.
Moreover, the two electrodes of the emitting element 121B1 and the two electrodes of the emitting element 122B1 are separately disposed along the X-axis direction on the dielectric substrate 130B. Each electrode of the emitting elements 121B1 and 122B1 has a substantially square shape and is disposed such that each side of the electrode is parallel to the X-axis or the Z-axis.
On each of the electrodes of the emitting elements 121B1 and 122B1, power supply points are disposed at a position offset from the center of the electrode in the positive direction of the X-axis and a position offset from the center of the electrode in the positive direction of the Z-axis. That is, from the individual electrodes, radio waves whose polarization direction is the X-axis direction and radio waves whose polarization direction is the Z-axis direction are emitted.
Even in the antenna module 100D, the emitting element 121A1 of the dielectric substrate 130A for the lower frequency band is disposed at a position that is farther from the dielectric substrate 130B than the emitting element 122A1 for the higher frequency band is. Thus, the deterioration of isolation can be suppressed even in the antenna module 100D.
Note that, in the above-described embodiment and each modification, the “X-axis direction” corresponds to the “first direction” and the “third direction” according to the present disclosure, the “Y-axis direction” corresponds to the “second direction” according to the present disclosure, and the “Z-axis direction” corresponds to the “fourth direction” according to the present disclosure.
Note that, in the above-described embodiment and modifications, the configurations have been described in which the emitting elements 121 and 122 are separately disposed on the dielectric substrates; however, a configuration may be used in which a third emitting element corresponding to a frequency band (for example, 60 GHz) different from those of the emitting elements 121 and 122 is stacked on the emitting element 121 or the emitting element 122.
Moreover, in the above-described description, the cases where the emitting elements are patch antennas having flat plate-like shapes have been described; however, the emitting elements may be antennas having shapes other than patch antennas. For example, the emitting elements may be dielectric resonator antennas (DRAs).
The embodiments disclosed this time are to be considered exemplary and not restrictive in all respects. The scope of the present disclosure is indicated by the claims, not by the description of the embodiments above, and is intended to include all changes within the meaning and scope of the claims and those of equivalents of the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-146760 | Sep 2021 | JP | national |
This is a continuation application of PCT/JP2022/030092, filed on Aug. 5, 2022, designating the United States of America, which is based on and claims priority to Japanese Patent Application No. JP 2021-146760 filed on Sep. 9, 2021. The entire contents of the above-identified applications, including the specifications, drawings and claims, are incorporated herein by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP22/30092 | Aug 2022 | WO |
| Child | 18442131 | US |
