Patent Grant
11450942
The present disclosure relates to an antenna module and a communication device equipped with the same, and more particularly, to an antenna structure able to reduce an effective dielectric constant.
WO 2016/067969 (Patent Document 1) discloses an antenna module in which an antenna element and a radio frequency semiconductor element are integrated to be mounted on a dielectric substrate.
In such an antenna, antenna characteristics such as a frequency band width of a transmittable radio frequency signal, a peak gain, and loss are affected by a dielectric constant of a dielectric substrate on which an antenna element is mounted.
The loss characteristics of an antenna are generally considered to be improved as a relative dielectric constant (εr) and a dielectric loss tangent (tan δ) of a dielectric substrate are lower. Accordingly, in order to achieve a high peak gain of the antenna and reduce power consumption of the device, it is necessary to reduce a dielectric constant of the dielectric substrate.
On the other hand, as for the frequency band width, in general, as the thickness of the dielectric substrate (in other words, the distance between an antenna element and a ground electrode) increases, the frequency bandwidth becomes wider. In recent years, a mobile terminal such as a smart phone has been particularly required to be thinner, so that an antenna module itself has been needed to be downsized and thinned. However, when a dielectric substrate is thinned, there may arise a problem that the frequency band width of the antenna is narrowed.
The present disclosure has been conceived in order to solve the above described problem, and an object thereof is to achieve a wider band width and to lessen the loss in an antenna module.
An antenna module according to an aspect of the present disclosure includes at least one radiating element, a ground electrode, and a dielectric layer which is provided between the at least one radiating element and the ground electrode, and on which the at least one radiating element is mounted. A space is formed between the dielectric layer and the ground electrode in a region where the at least one radiating element and the ground electrode overlap each other when the dielectric layer is seen in a plan view.
Preferably, the dielectric layer has a first portion in which the at least one radiating element is disposed, and a second portion in which the at least one radiating element is not disposed. A thickness of the dielectric layer in a normal line direction in the second portion is thinner than a thickness of the dielectric layer in the normal line direction in the first portion.
Preferably, the antenna module further includes at least one feeding circuit and a feeding line. The at least one feeding circuit is mounted in or on the dielectric layer and is configured to supply radio frequency power to the at least one radiating element. The feeding line is formed in the dielectric layer, and transmits radio frequency power from the at least one feeding circuit to the at least one radiating element.
Preferably, the antenna module further includes at least one feeding circuit mounted in or on the dielectric layer and configured to supply radio frequency power to the at least one radiating element. The at least one feeding circuit is disposed in the first portion of the dielectric layer.
Preferably, the antenna module further includes at least one feeding circuit mounted in or on the dielectric layer and configured to supply radio frequency power to the at least one radiating element. The at least one feeding circuit is disposed in the second portion of the dielectric layer.
Preferably, the antenna module further includes at least one feeding circuit mounted in or on the dielectric layer and configured to supply radio frequency power to the at least one radiating element. The dielectric layer further has a third portion in which the thickness of the dielectric layer in the normal line direction is thicker than the thickness in the second portion, and which is different from the first portion. The at least one feeding circuit is disposed in the third portion.
Preferably, the antenna module further includes another radiating element disposed in the third portion. The at least one feeding circuit is disposed on a surface on the opposite side to a surface on which the other radiating element is disposed in the third portion.
Preferably, the at least one radiating element is more than one in number, and the plurality of radiating elements is disposed separate from one another in a planar direction of the dielectric layer. The feeding circuit is provided corresponding to each of the radiating elements.
Preferably, an upper surface of the second portion is continuously connected with a lower surface of the space formed in the dielectric layer.
Preferably, the ground electrode is formed on the lower surface of the space.
Preferably, when the dielectric layer is seen in a plan view, the entirety of the at least one radiating element overlaps the space described above.
Preferably, the dielectric layer has a first portion in which one end portion of the dielectric layer is bent to face, and a second portion in which the one end portion does not face. A thickness of the dielectric layer in a normal line direction in the second portion is thinner than a thickness of the dielectric layer in the normal line direction in the first portion.
Preferably, the dielectric layer bends in a direction orthogonal to an extending direction of the dielectric layer from the first portion to the second portion when seen in a plan view from the normal line direction of the dielectric layer. The bend is started in the space in the first portion.
A communication device according to another aspect of the present disclosure includes any one of the above-described antenna modules and a housing that is at least partially formed of resin. The at least one radiating element of the antenna module is disposed so as to face the resin portion in the housing.
In the antenna module according to the present disclosure, a space is formed between the dielectric layer on which the radiating element (antenna element) is disposed and the ground electrode, which makes it possible to reduce the effective dielectric constant from the radiating element to the ground electrode. Accordingly, in the antenna module, it is possible to achieve a wider band width and lessen the loss.
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Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Note that the same or corresponding constituent elements in the drawings are denoted by the same reference symbols, and the description thereof will not be repeated.
(Basic Configuration of Communication Device)
Referring to
In
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 synthesizer/demultiplexer 116, a mixer 118, and an amplification circuit 119.
When transmitting a radio 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 a transmission-side amplifier of the amplification circuit 119. When receiving a radio 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 a reception-side amplifier of the amplification circuit 119.
A signal transmitted from the BBIC 200 is amplified by the amplification circuit 119, and is up-converted by the mixer 118. The transmission signal, which is an up-converted radio frequency signal, is demultiplexed by the signal synthesizer/demultiplexer 116 into four signals, and the demultiplexed signals are respectively fed, passing through four signal paths, to the different antenna elements 121. At this time, the directivity of the antenna array 120 may be adjusted by individually adjusting the phase shift degrees of the phase shifters 115A to 115D disposed in each of the corresponding signal paths.
Additionally, the reception signals, which are radio frequency signals received by each of the antenna elements 121, respectively pass through the four different signal paths, and then multiplexed by the signal synthesizer/demultiplexer 116. The multiplexed reception signal is down-converted by the mixer 118, amplified by the amplification circuit 119, and then transmitted to the BBIC 200.
The RFIC 110 is formed as, for example, a single chip integrated circuit component including the above-described circuit configuration. Alternatively, the units (switches, power amplifiers, low-noise amplifiers, attenuators, and phase shifters) in the RFIC 110 corresponding to each of the antenna elements 121 may be formed as a single chip integrated circuit component for each corresponding antenna element 121.
(Structure of Antenna Module)
The first dielectric layer 130 and the second dielectric layer 135 (hereinafter, also collectively referred to as “dielectric layer”) are formed of, for example, resin such as epoxy, polyimide or the like. Also, the dielectric layer may be formed by using a liquid crystal polymer (LCP) having a lower dielectric constant or fluorine-based resin.
The second dielectric layer 135 is formed in a flat plate shape, for example, and the ground electrodes GND1 and GND2 are laminated on front and rear surfaces thereof, respectively.
The first dielectric layer 130 is partially disposed on the ground electrode GND1, and the antenna element 121 is disposed on a front surface of the first dielectric layer 130. In
The RFIC 110 is disposed so as to be in contact with the ground electrode GND2. A radio frequency signal outputted from the RFIC 110 is transmitted, through a feeding line 140, to the antenna element 121. The feeding line 140 is connected to the antenna element 121 while passing through the second dielectric layer 135 and further passing through the first dielectric layer 130.
In
In the first dielectric layer 130, a space 132 is partially formed in a thickness direction (the normal line direction of the dielectric layer). When the dielectric layer is seen in a plan view, the antenna element 121 is disposed such that at least part thereof overlaps a region where the space 132 is formed. It is more preferable that the overall antenna element 121 overlap with the space 132.
The lower boundary of the space 132 in the first portion 151 is the ground electrode GND1, and is continuously connected with the upper surface of the second portion 152.
The reason why the space 132 is provided between the first dielectric layer 130 and the second dielectric layer 135 will be described below with reference to a comparative example in
Here, as the characteristics of an antenna module, it is generally required to widen a frequency band width that can be transmitted and received, and to lessen the loss when a radio frequency signal is transmitted. It is generally known that the loss characteristics of an antenna are improved as a relative dielectric constant (εr) and a dielectric loss tangent (tan δ) of a dielectric layer where the antenna element is disposed are lower; therefore, in order to achieve a high peak gain of the antenna and reduce the power consumption of the device, it is necessary to reduce the dielectric constant of the dielectric layer.
On the other hand, as for widening the band width, it is known that the thicker the thickness of the dielectric layer (i.e., the distance between the antenna element and the ground electrode) is, the wider the band width becomes. In recent years, a mobile terminal such as a smart phone has been particularly required to be thinner, so that an antenna module itself has been needed to be thinned. However, when the dielectric layer is thinned in order to achieve a reduction in thickness, the frequency band width of the antenna may be narrowed.
In the antenna module 100# of the comparative example in
On the other hand, in the first embodiment illustrated in
As in the first embodiment, by forming the space 132 in the first dielectric layer 130, the effective dielectric constant between the antenna element 121 and the ground electrode GND1 may be reduced, and thus the frequency band width and the antenna gain may be improved. Alternatively, by reducing the thickness of the first dielectric layer 130, it is also possible to further reduce the effective dielectric constant and achieve a lower profile.
When the antenna module 100A is seen in a plan view from the normal line direction of the dielectric layer, a portion where the third dielectric layer 130A is disposed is referred to as a third portion 153. In the third portion 153 in
In
(Specific Example of First Dielectric Layer)
Next, some examples of the structure of the first dielectric layer that forms the space will be described with reference to
In an example of
Each of
In an example of a first dielectric layer 130C illustrated in
Note that, in any of
For each of the antenna elements 121, the RFIC 110 is arranged on the ground electrode GND1 separated in an X direction in
As described above, in the antenna module, by providing a space between the antenna element and the ground electrode in a portion of the dielectric layer where the antenna element is disposed, it is possible to reduce the effective dielectric constant while securing the distance between the antenna element and the ground electrode. This makes it possible to lessen the loss and improve the antenna performance while maintaining the frequency band width.
(Manufacturing Process)
Next, a manufacturing process of the antenna module according to the first embodiment will be described with reference to
(First Process Example)
Each of
First, referring to
The first dielectric layer 130 is formed by laminating a first layer 130_1 on which the antenna elements 121 and 121A are to be disposed, and a second layer 130_2 in which the space 132 is to be formed. First, the second layer 130_2 is laminated on the ground electrode GND1. At this time, a member 150 of a material different from that of the first dielectric layer 130, such as stainless steel, is disposed in a portion where the space 132 is to be formed.
The first layer 130_1 is laminated on the second layer 130_2, and further the antenna elements 121 and 121A are disposed on the first layer 130_1. The RFIC 110 is disposed on the ground electrode GND2 on the rear surface side of the second dielectric layer 135.
Thereafter, as illustrated in
Then, the member 150 is extracted from a portion in a space 155 where the first dielectric layer 130 has been removed, whereby the space 132 is formed under the antenna element 121 (
Note that, in the above explanation, a case in which the member 150 is physically extracted is described. However, for example, the member 150 may be formed of resin or the like that can be dissolved, and may be chemically removed by etching.
As described above, in the manufacturing process of
(Second Process Example)
Each of
First, referring to
Thereafter, the first portion 151 of the first dielectric layer 130 and the third portion 153 of the first dielectric layer 130A formed in
As described above, in
The process of the second example is particularly effective in a case where the support portion is formed on four sides of the space as illustrated in
(Third Process Example)
Each of
First, referring to
Furthermore, the third dielectric layer 130A is laminated on the ground electrode GND1 and the antenna element 121A is further laminated thereon, whereby the third portion 153 is formed. Then, the RFIC 110 is disposed on the ground electrode GND2 (
Note that, in the above description, the third portion is formed by the laminated structure, but may be formed by bending the other end portion of the dielectric layer, similarly to the first portion. At this time, in a case where a space such as the first portion is unnecessary, the bent dielectric layer and the ground electrode GND1 are brought into close contact with each other.
As described above, in
(Example of Attachment to Communication Device)
Referring to
The antenna elements 121 and 121A of the antenna module 100A radiate radio waves to the outside of the communication device 10, and are each disposed in a position close to a housing 20 of the communication device 10 in order to receive radio waves from the outside.
Since a metal material may generally function as a shield against radio waves, when the housing 20 is formed of a metal material, resin portions 30 made of resin capable of passing radio waves therethrough are partially formed, and the antenna elements 121 and 121A are disposed so as to face the resin portions 30 respectively. As a result, it is possible to appropriately transmit and receive the radio waves while being unlikely to be affected by the metal housing. Note that there may be a gap between each of the antenna elements 121, 121A and 121B, and each of the resin portion 30.
In a case where the whole housing 20 is formed of resin, the antenna elements 121 and 121A may be disposed in any positions.
In the antenna module of the first embodiment, described is the configuration in which the dielectric layer on which the antenna element is disposed has a substantially rectangular shape when seen in a plan view, and the two antenna elements in
The antenna module may be used in a small and thin communication device such as a smart phone, and may be required to be disposed in a limited space in the device. In this case, depending on an attachment location of the antenna module, it may be necessary to dispose two antenna elements by offsetting the antenna elements. By doing so, in the linear antenna arrangement, there is a possibility that mechanical stress is applied to the dielectric layer and a crack or the like is generated in the dielectric layer.
Then, in the second embodiment, a configuration is described in which a dielectric layer of an antenna module is formed in a crank shape and two antenna elements are offset and disposed.
Each of
Referring to
Here, a bend start point SP on the first portion 151 side is set in the space 132 in the first portion 151. By doing so, the curvature of the bent portion of the second dielectric layer 135B may be made to be gentler than that in a case where a boundary between the first portion 151 and the second portion 152 is set as the start point. As a result, mechanical stress applied to the second dielectric layer 135B may be reduced when the antenna module 100B is attached or the like.
Note that, in the above-described embodiments, the configuration in which the radiating element is disposed on the front surface of the dielectric layer is cited as an example and described. However, the radiating element may be configured to be disposed inside the dielectric layer. That is, the radiating element may not be exposed from the dielectric layer, and may be covered with a resist or a coverlay, which is a thin-film dielectric layer. Likewise, a ground electrode may also be configured to be formed inside the dielectric layer.
In the above-described embodiments, an example is described in which a portion of each of the dielectric layers 130E, 135, and 135B through which the feeding line from the RFIC 110 passes forms a strip line, where the ground electrodes are disposed on both surfaces of the dielectric layer. However, these dielectric layers may be formed as a microstrip line, where the ground electrode is disposed on only one side of the dielectric layer, or as a coplanar line, where the ground electrode and the feeding line are disposed in the same layer in the dielectric layer.
It is to be noted that the embodiments disclosed herein are illustrative in all respects and are not restrictive. The scope of the present disclosure is indicated by the claims rather than the description of the above-described embodiments, and it is intended to include all meanings equivalent to the claims and all modifications within the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| JP2018-029845 | Feb 2018 | JP | national |
This is a continuation of International Application No. PCT/JP2019/002029 filed on Jan. 23, 2019 which claims priority from Japanese Patent Application No. 2018-029845 filed on Feb. 22, 2018. The contents of these applications are incorporated herein by reference in their entireties.
| Number | Name | Date | Kind |
|---|---|---|---|
| 20170222316 | Mizunuma et al. | Aug 2017 | A1 |
| 20170229769 | Yokoyama et al. | Aug 2017 | A1 |
| 20190067219 | Lasiter | Feb 2019 | A1 |
| Number | Date | Country |
|---|---|---|
| 05-152831 | Jun 1993 | JP |
| H06-283924 | Oct 1994 | JP |
| 2005-051329 | Feb 2005 | JP |
| 2013-187731 | Sep 2013 | JP |
| 2016063759 | Apr 2016 | WO |
| 2016067969 | May 2016 | WO |
| Entry |
|---|
| International Search Report issued in Application No. PCT/JP2019/002029, dated Mar. 5, 2019. |
| Written Opinion issued in Application No. PCT/JP2019/002029, dated Mar. 5, 2019. |
| Number | Date | Country | |
|---|---|---|---|
| 20200373646 A1 | Nov 2020 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2019/002029 | Jan 2019 | US |
| Child | 16992463 | US |
