WO2017208557A1

WO2017208557A1 - Antenna device and radio

Info

Publication number: WO2017208557A1
Application number: PCT/JP2017/009870
Authority: WO
Inventors: 弘泰末竹; 武部　裕幸
Original assignee: シャープ株式会社
Priority date: 2016-06-03
Filing date: 2017-03-13
Publication date: 2017-12-07
Also published as: CN109155461B; JP6651010B2; JPWO2017208557A1; CN109155461A

Abstract

The present invention inhibits deterioration in antenna performance of an antenna element disposed in a position enclosed in a metallic frame. This antenna device (1) is provided with: a first antenna element (12) that operates in a first frequency band; a first electricity supply unit (11) connected to the first antenna element (12); and a metallic frame (14), wherein the first electricity supply unit (11) and the metallic frame (14) are connected via a first impedance control unit (13) that controls impedance in the first frequency band.

Description

Antenna device and radio

One embodiment of the present invention relates to an antenna device and a wireless device, and particularly relates to an antenna device including a metal frame and a wireless device including the antenna device.

In an antenna device having a metal frame and having an antenna element disposed therein, the antenna characteristics of the internal antenna element are significantly deteriorated due to shielding by the metal frame. In order to reduce this, in the technique described in Patent Document 1, an antenna element is arranged in an opening provided in a metal frame.

International Publication WO2015 / 166800 Pamphlet

However, in the technique described in Patent Document 1, it is necessary to arrange an antenna element near the opening provided in the metal frame, so that the degree of freedom of antenna arrangement is reduced. Even when the antenna element is disposed at a position surrounded by the metal frame, it is beneficial if the deterioration of the antenna characteristics can be suppressed.

One aspect of the present invention has been made in view of the above problems, and a main object thereof is to provide a technique for suppressing deterioration of antenna characteristics of an antenna element arranged at a position surrounded by a metal frame.

An antenna device according to an aspect of the present invention surrounds a first antenna element that operates in a first frequency band, a first feeding unit connected to the first antenna element, and the first antenna element. The first power supply unit and the metal frame are connected via a first impedance control unit that controls impedance in the first frequency band.

According to one aspect of the present invention, it is possible to suppress deterioration of antenna characteristics of an antenna element arranged at a position surrounded by a metal frame.

(A) is sectional drawing which shows schematic structure of the antenna device which concerns on one Embodiment (Embodiment 1) of this invention, (b) is a figure which shows the flow of the high frequency current in the said antenna device. (A) is side sectional drawing which shows the internal structure of the antenna apparatus which concerns on one Embodiment (Embodiment 1) of this invention, (b) and (c) show the variation of the external appearance of the said antenna apparatus. It is a side view. It is sectional drawing which shows the ground in the antenna apparatus which concerns on one Embodiment (Embodiment 1) of this invention. It is a figure which shows the structural example of the impedance control part in the antenna device which concerns on one Embodiment (Embodiment 1) of this invention. It is sectional drawing which shows the variation of schematic structure of the antenna apparatus which concerns on one Embodiment (Embodiment 2) of this invention. It is a figure which shows the structural example of the impedance control part in the antenna device which concerns on one Embodiment (Embodiment 2) of this invention. It is sectional drawing which shows schematic structure of the antenna device which concerns on one Embodiment (Embodiment 3) of this invention. It is sectional drawing which shows the modification of schematic structure of the antenna device which concerns on one Embodiment (Embodiment 3) of this invention. It is sectional drawing which shows schematic structure of the antenna device which concerns on one Embodiment (Embodiment 4) of this invention. It is sectional drawing which shows the ground in the antenna apparatus which concerns on one Embodiment (Embodiment 4) of this invention. (A) is sectional drawing which shows schematic structure of the antenna device which concerns on one Embodiment (Embodiment 5) of this invention, (b) is a figure which shows the flow of the high frequency current in the said antenna device. It is sectional drawing which shows schematic structure of the antenna apparatus which concerns on the Example and comparative example of this invention. It is a graph which shows the characteristic of the filter used in the Example of this invention. It is a graph which shows the result of the Example and comparative example of this invention. It is a graph which shows the result of the Example and comparative example of this invention.

The present inventors have intensively studied to provide a technique for suppressing deterioration of antenna characteristics of an antenna element arranged at a position surrounded by a metal frame.

First, when an antenna element is simply placed at a position surrounded by a metal frame, the antenna characteristics of the antenna element are greatly deteriorated because the antenna element is shielded by the metal frame.

Next, the present inventors examined supplying power simultaneously to the antenna element and the metal frame. In this case, it was expected that the metal frame can function as a part of the antenna in addition to the antenna element, and the influence of shielding the metal frame can be reduced. Also, it was expected that the resonance frequency of the antenna element could be easily adjusted by adjusting the length of the antenna element. However, the antenna characteristics when power is supplied to the antenna element and the metal frame at the same time depend on the design conditions of the metal frame (such as the connection conditions between the metal frame and the power supply unit), and the design of the metal frame resonates with the antenna element. When the antenna excitation conditions are not good in the desired frequency band, it has been confirmed that it is difficult to secure the antenna characteristics no matter how much the length of the antenna element is adjusted or the antenna matching circuit is adjusted. This is considered to be because when the power is supplied to the antenna element and the metal frame at the same time, the excitation condition of the antenna of the metal frame becomes dominant because the metal frame is positioned on the outermost side of the antenna device rather than the arrangement of the antenna element. .

Here, when the metal frame itself operates as an antenna, the structure around the metal frame also affects the antenna characteristics. Furthermore, since the corresponding wavelength becomes shorter in the high frequency band, even a small structure around the metal frame affects the antenna characteristics. Therefore, when configuring an antenna device that covers a high frequency band, the mechanical structure also has a size that cannot be ignored with respect to the antenna characteristics, and the metal frame is designed as an antenna as intended by the designer. It was very difficult.

Therefore, the inventors of the present invention made extensive studies and surrounded the metal element by connecting the power feeding part of the antenna element and the metal frame via the impedance control unit that controls the impedance in the use frequency band of the antenna element. The present inventors have found that it is possible to suppress the deterioration of antenna characteristics of the antenna elements arranged at the positions, and completed one embodiment of the present invention.

That is, by connecting the power feeding part of the antenna element and the metal frame via an impedance control part that controls the impedance in the use frequency band of the antenna element, the direction opposite to the direction of the high-frequency current flowing through the antenna element is obtained. Adjustment can be made so that the high-frequency current does not flow through the metal frame, the metal frame can be prevented from inhibiting radiation of the antenna element, and deterioration of the antenna characteristics of the antenna element can be suppressed. Or the antenna characteristic of an antenna element can be improved because the high frequency current of the same direction flows into a metal frame with respect to the direction of the high frequency current which flows into an antenna element.

Hereinafter, embodiments of the present invention will be described in detail. However, unless otherwise specified, the configuration described in the present embodiment is merely an illustrative example, and is not intended to limit the scope of the present invention.

Embodiment 1
An antenna device according to an embodiment (Embodiment 1) of the present invention will be described with reference to the drawings. The antenna device according to an embodiment of the present invention may be an antenna device provided in a wireless device such as a mobile phone terminal, a portable information terminal, a smartphone, a tablet terminal, and a mobile PC terminal, but is not limited thereto. The present invention can be applied to any antenna device having a metal frame.

(Antenna device 1)
(A) of FIG. 1 is sectional drawing which shows schematic structure of the antenna apparatus 1 which concerns on this embodiment. As shown in FIG. 1A, the antenna device 1 includes a first power feeding unit 11, a first antenna element 12, a first impedance control unit 13, and a metal frame 14. The antenna device 1 is configured as a part of a wireless device including the antenna device 1 and the wireless circuit unit 10.

The radio circuit unit 10 includes a filter, an amplifier, a modulation unit, a demodulation unit, an A / D conversion unit, a D / A conversion unit, an amplifier, and the like, and processes a high-frequency signal for wireless communication. The radio circuit unit 10 is connected to the first power supply unit 11. The first power feeding unit 11 is connected to the first antenna element 12 and is connected to the metal frame 14 via the first impedance control unit 13.

The first antenna element 12 operates in the first frequency band. That is, the first power supply unit 11 inputs and outputs a high-frequency signal in the first frequency band, and feeds the antenna to the first antenna element 12. As a result, the first antenna element 12 can be used to transmit and receive high-frequency signals in the first frequency band. At this time, it is more preferable that the first antenna element 12 resonates in the first frequency band.

The first frequency band is not particularly limited. For example, the first frequency band is preferably 2.4 GHz or more, more preferably 3.4 GHz or more, and more preferably 5 GHz or more. Particularly preferred. As the frequency becomes higher, even a small structure in the antenna device 1 appears to be a size that cannot be ignored, and the antenna design becomes more difficult. Therefore, the superiority of the embodiment of the present invention becomes remarkable. Specific examples of the first frequency band include, for example, Wi-Fi (registered trademark) 2.4 GHz band, Wi-Fi (registered trademark) 5 GHz band, LTE band 41 (2496 to 2690 MHz), LTE band 42 (3400 to 3600 MHz). , LTE band 43 (3600-3800 MHz) and the like, but are not limited thereto.

The impedance control unit 13 is a circuit or element that controls impedance in the first frequency band. “Controlling the impedance in the first frequency band” is intended to control the impedance of the path in which the impedance control unit 13 is inserted to a desired value (imaginary number) with respect to the first frequency band. is doing.

In the present embodiment, the first impedance control unit 13 exhibits high impedance in the first frequency band. “Show high impedance in the first frequency band” means that the attenuation of the high-frequency signal in the first frequency band that has passed through the impedance control unit 13 is −15 dB or less. In other words, it means that the through characteristic of the first impedance control unit 13 is −15 dB or less. In one embodiment, the attenuation of the high-frequency signal in the first frequency band that has passed through the impedance control unit 13 is −10 dB or less, more preferably −20 dB or less, and particularly preferably −25 dB or less. Further, the maximum value of the attenuation is not particularly limited, but the attenuation may be, for example, −50 dB or more.

The metal frame 14 forms the side wall of the housing of the antenna device 1, and the internal configuration of the antenna device 1 (the radio circuit unit 10, the first power feeding unit 11, the first antenna element 12, and the first antenna element 1). The impedance control unit 13) is enclosed.

In the antenna device 1 according to the present embodiment, the first feeding unit 11 and the metal frame 14 are connected via the first impedance control unit 13 that exhibits high impedance in the first frequency band. Thereby, it can suppress that the antenna characteristic of the 1st antenna element 12 deteriorates with the metal frame 14 arrange | positioned so that the 1st antenna element 12 may be enclosed.

This will be described in detail with reference to FIG. FIG. 1B is a diagram illustrating the direction of high-frequency current flow in the antenna device 1. The metal frame 14 is connected to the first power feeding unit 11 that inputs and outputs a high-frequency signal in the first frequency band via the first impedance control unit 13, but the first impedance control unit 13 Since it operates so as to exhibit high impedance in the first frequency band, it is possible to prevent the high-frequency current in the first frequency band from flowing through the metal frame 14. Thereby, as shown in FIG. 1B, the high-frequency current I1 flowing in the metal frame 14 flows in the opposite direction with respect to the direction in which the high-frequency current I0 of the first antenna element 12 flows in the first frequency band. Therefore, it is possible to prevent the metal frame 14 from hindering the operation of the first antenna element 12.

Therefore, it is possible to suppress the deterioration of the antenna characteristics of the first antenna element 12 by the metal frame 14. For example, the antenna efficiency of the first antenna element 12 can be improved and the bandwidth can be increased. it can. And in order to acquire said effect, since it becomes unnecessary to adjust (change) the connection conditions of the metal frame 14, arrangement | positioning of the structure close to the metal frame 14, etc., there exists an effect which the freedom degree of antenna design improves. .

2A is a side sectional view showing an example of the internal configuration of the antenna device 1. FIG. As shown in FIG. 2A, in one embodiment, the antenna device 1 may further include a substrate (ground) 15, a liquid crystal panel 16, and a back panel 17. A radio circuit unit 10 is formed on the substrate 15, and is connected to the first antenna element 12 via the first power feeding unit 11. The substrate 15, the first power feeding unit 11, and the first antenna element 12 are disposed between the liquid crystal panel 16 and the non-metallic back panel 17, and the substrate 15 is disposed on the liquid crystal panel 16 side. The first antenna element 12 is preferably disposed on the panel 17 side. According to this embodiment, although the influence of the shielding of the metal frame 14 on the first antenna element 12 can be suppressed, the height (antenna height) of the first antenna element 12 from the substrate (ground) 15 can be suppressed. This is because a structure that can assure as much as possible is better in terms of antenna characteristics.

(B) and (c) of FIG. 2 are side views showing variations in the appearance of the antenna device. As shown in FIG. 2B, the metal frame 14 may exist over the entire thickness direction of the antenna device 1, or as shown in FIG. On the other hand, resin layers may be provided above and below.

(ground)
FIG. 3 is a cross-sectional view showing the substrate 15 in one embodiment. In the antenna device 1, the substrate 15 also functions as a ground. Then, the ground (substrate 15) is removed from the portion A that faces the arrangement location of the first impedance control unit 13 on the surface on which the ground (substrate 15) is provided. Thereby, the 1st impedance control part 13 can adjust an impedance suitably.

That is, when the ground is not removed from the portion A and the first impedance control unit 13 and the ground are close to each other, the first impedance control unit 13 and the ground may be capacitively coupled. When the first impedance control unit 13 and the ground are capacitively coupled, it is difficult to adjust the impedance to a high impedance particularly in a high frequency band. On the other hand, since the first impedance control unit 13 and the ground can be prevented from being capacitively coupled by removing the ground from the portion A, the first impedance control unit 13 has a suitable impedance. Can be adjusted.

Note that the ground provided in the antenna device 1 is not limited to the substrate 15, and may be provided on one or more surfaces defined in the antenna device 1. In this case, it is preferable that the ground is removed from the portion of the one or more surfaces facing the first impedance control unit 13. Thereby, as above-mentioned, the 1st impedance control part 13 can adjust an impedance suitably.

Also, for the same reason, it is preferable that the path connected from the metal frame 14 to the first power supply unit 11 via the first impedance control unit 13 is short. Since the influence of the metal member existing around the route can be reduced by connecting the route short, the first impedance control unit 13 can adjust the impedance more suitably. For example, as shown in FIG. 4A, a portion 14 a drawn from the metal frame 14 may be directly connected to the first impedance control unit 13 as a method for connecting the paths short.

(Impedance control unit 13)
In one embodiment, the first impedance control unit 13 includes one or more selected from the group consisting of a notch filter, a band elimination filter, and a low pass filter. By using such a filter, it is possible to suitably realize the first impedance control unit 13 that exhibits high impedance in the first frequency band.

FIG. 4A shows an example in which the first impedance control unit 13 is configured by a notch filter. In the example shown in FIG. 4A, the notch filter has a configuration in which a capacitor C1 and an inductor L1 are connected in parallel. For example, by adjusting the capacitance of the capacitor C1 and the inductance of the inductor L1 based on the following expression, the center frequency at which the notch filter shown in FIG. it can.
f = 1 / 2π√ (LC)
(F: center frequency, L: inductance, C: capacitance)
FIG. 4B shows an example in which the first impedance control unit 13 is configured by a low-pass filter. In the example shown in FIG. 4B, the low-pass filter has an inductor L4 inserted on the path between the metal frame 14 and the first power feeding unit 11, and a path that branches from the path and grounds. And an inserted capacitor C4. By adjusting the capacitance of the capacitor C4 and the inductance of the inductor L4, it is possible to arbitrarily set the frequency band in which the low-pass filter shown in FIG. 4B has a high impedance.

[Embodiment 2]
The second embodiment of the present invention will be described as follows. In addition, the description about the member demonstrated in Embodiment 1 is abbreviate | omitted. FIG. 5 is a cross-sectional view showing a variation of the schematic configuration of the antenna device 2 according to the present embodiment. The antenna device 2 is configured as a part of a wireless device including the antenna device 2 and the wireless circuit unit 10.

The antenna device 2 according to the present embodiment is different from the antenna device 1 in that it can transmit and receive high-frequency signals in the first frequency band and the second frequency band, respectively.

For example, in the antenna device 2 shown in FIG. 5A, in addition to the first antenna element 12, a second antenna element 22 is connected to the first feeding unit 11.

The first antenna element 12 operates in the first frequency band, and the second antenna element 22 operates in a second frequency band different from the first frequency band. That is, the first power feeding unit 11 inputs and outputs a high frequency signal in the second frequency band in addition to the high frequency signal in the first frequency band, and the first antenna element 12 and the second antenna element 22. Are fed simultaneously with the antenna. As a result, the first antenna element 12 can be used to transmit and receive high-frequency signals in the first frequency band, and the second antenna element 22 can be used to transmit and receive high-frequency signals in the second frequency band. At this time, it is more preferable that the first antenna element 12 resonates in the first frequency band, and it is more preferable that the second antenna element 22 resonates in the second frequency band.

Further, for example, as shown in FIGS. 5B and 5B, the antenna device 2 may not include the second antenna element 22. In this case, the first antenna element 12 has a shape of at least one turn, and is configured so that the higher-order mode (resonance of the second harmonic or higher) of the fundamental wave of the first antenna element 12 can be easily adjusted. It is preferable. With this configuration, for example, the first antenna element 12 operates in the first frequency band corresponding to the fundamental wave of the first antenna element 12, and the third harmonic of the first antenna element 12 is used. It can be configured to operate in a second frequency band corresponding to. Further, for example, the first antenna element 12 operates in the first frequency band corresponding to the third harmonic of the first antenna element 12 and the second antenna corresponding to the fifth harmonic of the first antenna element 12. You may comprise so that it may operate | move in the frequency band. In addition, the first antenna element 12 may be configured to operate in any two frequency bands selected from the fundamental wave of the first antenna element 12 and each higher-order mode.

And the 1st impedance control part 23 with which the antenna apparatus 2 is provided shows a high impedance also in a 2nd frequency band further in addition to a 1st frequency band. Thereby, when the 1st electric power feeding part 11 carries out antenna electric power feeding of the metal frame 14 via the 1st impedance control part 23, the high frequency current of a 1st frequency band and a 2nd frequency band is supplied to the metal frame 14. Each can be prevented from flowing. Thereby, it is possible to prevent the high-frequency current flowing in the metal frame 14 from flowing in the reverse direction with respect to the direction in which the high-frequency current of the first antenna element 12 in the first frequency band flows. Since the high-frequency current flowing through the metal frame 14 can be prevented from flowing in the reverse direction even with respect to the direction in which the high-frequency current flows through the first antenna element 12 or the second antenna element 22 in the frequency band, the metal frame 14 can inhibit the operation of the first antenna element 12 (and the operation of the second antenna element 22) from being hindered.

As described above, the internal configuration of the antenna device 2 (the wireless circuit unit 10, the first power feeding unit 11, the first antenna element 12, the second antenna element 22, and the first impedance control unit 23) is surrounded. The disposed metal frame 14 can suppress the deterioration of the antenna characteristics of the first antenna element 12 (and the second antenna element 22).

(First impedance control unit 23)
Moreover, the 1st impedance control part 23 is the structure by which the filter which shows high impedance in a 1st frequency band and the filter which shows high impedance in a 2nd frequency band are connected in series in one Embodiment. Including. By using this configuration, the first impedance control unit 23 that exhibits high impedance in the first frequency band and the second frequency band can be suitably realized. Each filter can be, for example, a filter selected from the group consisting of a notch filter, a band elimination filter, and a low pass filter.

FIG. 6 shows an example in which the first impedance control unit 23 is configured by two notch filters. In the example shown in FIG. 6, a notch filter having a configuration in which a capacitor C2 and an inductor L2 are connected in parallel and a notch filter having a configuration in which a capacitor C3 and an inductor L3 are connected in parallel are connected in series. Yes. Adjusting one notch filter to show high impedance in the first frequency band and adjusting the other notch filter to show high impedance in the second frequency band, the first frequency band and The first impedance control unit 23 exhibiting high impedance in the second frequency band can be suitably realized.

(Modification)
In the modification, the number of antenna elements connected to the first power feeding unit 11 is not limited to two. Three or more antenna elements may be connected to the first feeding unit 11. In that case, the first impedance control unit 23 only needs to show a high impedance in the use frequency band of each antenna element. For example, the first impedance control unit 23 is connected to the use frequency band of each antenna element. What is necessary is just to comprise by connecting the filter which shows high impedance in series. By configuring in this way, it is possible to suppress deterioration of the antenna characteristics of each antenna element due to the influence of the metal frame 14.

Similarly to the ground provided in the antenna device 1, the ground provided in the antenna device 2 is provided on one or more surfaces defined in the antenna device 2, and the first impedance in the one or more surfaces is provided. It is preferable that the ground is removed from the portion facing the control unit 23. Thereby, the 1st impedance control part 23 can adjust an impedance suitably.

[Embodiment 3]
The third embodiment of the present invention will be described as follows. In addition, the description about the member demonstrated in Embodiment 1 is abbreviate | omitted. FIG. 7 is a cross-sectional view illustrating a schematic configuration of the antenna device 3 according to the present embodiment. The antenna device 3 is configured as a part of a wireless device including the antenna device 3 and the wireless circuit unit 10.

As shown in FIG. 7, in the antenna device 3 according to the present embodiment, the first power feeding unit 11 feeds the first antenna element 12 in the same manner as the antenna device 1 according to the first embodiment. One antenna element 12 operates in the first frequency band, and the metal frame 14 is fed by the antenna via the first impedance control unit 13 that exhibits high impedance in the first frequency band. Thereby, it can suppress that the antenna characteristic of the 1st antenna element 12 deteriorates with the metal frame 14. FIG.

Further, in the antenna device 3, the metal frame 14 is provided with a slit 36 for using the metal frame 14 as an antenna element that operates in a third frequency band lower than the first frequency band. That is, in the metal frame 14, the first portion sandwiched between the slit 36 and the connection point P <b> 1 to the first impedance control unit 13 in the metal frame 14, in other words, from the connection point P <b> 1 in the metal frame 14. The electrical length of the first portion up to the end point P2 adjacent to the slit 36 is in the range of 1/8 wavelength or more and 3/8 wavelength or less in the third frequency band, and more preferably, the electrical length is the third length. 1/4 wavelength (λ / 4) in the frequency band. By inserting the slit 36 in this way, the first portion operates as a 1/4 wavelength (λ / 4) monopole antenna and resonates in the third frequency band. It can be suitably used as an antenna element that operates in the frequency band. That is, in the present embodiment, the first feeding unit 11 further inputs and outputs a high-frequency signal in the third frequency band and feeds the metal frame 14 with an antenna. As a result, the metal frame 14 can be used to transmit and receive high-frequency signals in the third frequency band. Since the third frequency band is a frequency band lower than the first frequency band, it is not blocked by the first impedance control unit 13. The electrical length of the first part may be in the range of 1/8 wavelength or more and 3/8 wavelength or less, and within this range, the first part is generally a quarter wavelength (λ / 4) system. Operates as a monopole antenna.

Note that the slits 36 may be provided at a plurality of locations.

(Modification)
FIG. 8 is a cross-sectional view illustrating a schematic configuration of an antenna device 3 according to a modification. As shown in FIG. 8, in one modification, in the antenna device 3, the second part of the metal frame 14 located on the opposite side to the first part across the connection point P1 on the metal frame 14 is a metal It may be grounded via a constant adjustment unit 37 that adjusts the impedance of the frame 14. The constant adjustment unit 37 may be any unit that adjusts the impedance of the metal frame 14 and may be formed of, for example, a reactance element such as a capacitor or an inductor.

Thus, by adding the constant adjustment unit 37 to the metal frame 14, the frequency band in which the metal frame 14 resonates can be adjusted more easily. In addition, by adding the constant adjustment unit 37 to the metal frame 14, it is possible to more easily perform impedance adjustment for the first frequency band that is the resonance frequency of the first antenna element 12. That is, according to the above configuration, the metal frame 14 and the first antenna element 12 are grounded via a constant, and the frequency adjustment between the resonance frequency of the metal frame 14 and the resonance frequency of the antenna element 12 is easy. Can be done.

Also in the antenna device 3, as in the antenna device 2 according to the second embodiment, a plurality of antenna elements that operate in different frequency bands are connected to the first feeding unit 11, or the first antenna element 12 may operate in a plurality of frequency bands, and the first impedance control unit 13 may show high impedance in each frequency band.

Similarly to the ground provided in the antenna device 1, the ground provided in the antenna device 3 is provided on one or more surfaces defined in the antenna device 3, and the first impedance in the one or more surfaces is provided. The ground is preferably removed from the portion facing the control unit 13. Thereby, the 1st impedance control part 13 can adjust an impedance suitably.

[Embodiment 4]
Embodiment 4 of the present invention will be described as follows. In addition, the description about the member demonstrated in Embodiment 1 is abbreviate | omitted. FIG. 9 is a cross-sectional view illustrating a schematic configuration of the antenna device 4 according to the present embodiment. The antenna device 4 is configured as a part of a wireless device including the antenna device 4 and the wireless circuit unit 10.

As shown in FIG. 9, in the antenna device 4 according to the present embodiment, the radio circuit unit 10 includes a third antenna element 42 that is disposed at a position surrounded by the metal frame 14 and operates in the fourth frequency band. A second power feeding part 41 connected to the third antenna element 42, and the second power feeding part 41 and the metal frame 14 are a second one that exhibits high impedance in the fourth frequency band. It may be configured to be electrically connected via the impedance control unit 43.

By comprising in this way, the 1st electric power feeding part 11 is connected to the metal part 14 via the 1st impedance control part 13 which shows a high impedance in a 1st frequency band, A 1st antenna By suppressing the deterioration of the antenna characteristics of the element 12, the second feeding unit 41 is connected to the metal unit 14 via the second impedance control unit 43 that exhibits high impedance in the fourth frequency band. Deterioration of the antenna characteristics of the third antenna element 42 can be suppressed.

Furthermore, since the antenna device 4 can be provided with the first feeding unit 11 including the first antenna element 12 and the second feeding unit 41 including the third antenna element 42 in different systems, each communication system is different. Application to is possible. Further, when used in the same communication system, the resonant frequency of the first antenna element 12 and the resonant frequency of the third antenna element 42 can be made substantially the same, for example, to operate as 2 × 2 MIMO. In general, when two antennas are adjusted at the same resonance frequency, the mutual isolation characteristics are increased and the correlation coefficient is increased. Therefore, in the configuration in which the metal frame 14 is antenna-fed from the first power supply unit 11 and the second power supply unit 41 and the metal frame 14 is shared as an antenna, mutual isolation characteristics may be increased. . However, in Embodiment 4 of this invention, the 1st electric power feeding part 11 is connected to the metal part 14 via the 1st impedance control part 13 which shows a high impedance in a 1st frequency band, and is the 2nd electric power feeding. Since the part 41 is connected to the metal part 14 via the second impedance control part 43 showing high impedance in the fourth frequency band, the high frequency current at the same resonance frequency of the two antennas is mutually connected to the metal frame. Therefore, interference between antennas can be suppressed, mutual isolation characteristics can be secured, and a correlation coefficient can be reduced. Thereby, even when used in the same communication system, a MIMO antenna can be preferably configured.

(ground)
FIG. 10 is a cross-sectional view showing the configuration of the substrate (ground) 45 of the antenna device 4 according to one embodiment. In the present embodiment, the portion A that faces the placement location of the first impedance control unit 13 and the portion that faces the placement location of the second impedance control unit 43 on the surface on which the ground (substrate 45) is provided. From B, the ground (substrate 45) is removed. Thereby, the 1st impedance control part 13 and the 2nd impedance control part 43 can avoid impedance coupling with a ground, and can adjust an impedance suitably. The ground provided in the antenna device 4 is not limited to the substrate 45, and may be provided on one or more surfaces defined in the antenna device 4. In this case, it is preferable that the ground is removed from a portion facing the first impedance control unit 13 and the second impedance control unit 43 on the one or more surfaces.

(Modification)
The antenna device 4 may include one or more sets of additional antenna elements, power feeding units, and impedance control units. In other words, three or more power feeding units may be provided, and each power feeding unit may be connected to the metal frame 14 via an impedance control unit corresponding to each. In this case, it is preferable that the ground is removed from a position facing each impedance control unit on the surface where the ground is provided.

Also in the antenna device 4, similarly to the antenna device 2 according to the second embodiment, a plurality of antenna elements are connected to the first feeding unit 11 or the second feeding unit 41, and the first impedance control unit 13. Or the 2nd impedance control part 43 may show a high impedance in the use frequency band of each antenna element.

Also in the antenna device 4, similarly to the antenna device 3 according to the third embodiment, the metal frame 14 is provided with the slit 36, and the metal frame 14 is configured to be used as an antenna element that operates in the third frequency band. May be. The slits 36 may be provided at a plurality of locations.

[Embodiment 5]
The fifth embodiment of the present invention will be described as follows. In addition, the description about the member demonstrated in Embodiment 1 is abbreviate | omitted. (A) of FIG. 11 is sectional drawing which shows schematic structure of the antenna apparatus 5 which concerns on this embodiment. The antenna device 5 is configured as a part of a wireless device including the antenna device 5 and the wireless circuit unit 10.

As shown to (a) of FIG. 11, in the antenna device 5 which concerns on this embodiment, the 1st impedance control part 53 is provided with the phase shifter which changes the phase of the high frequency signal of a 1st frequency band. . The first impedance control unit 53 changes the phase of the high-frequency signal in the first frequency band so that the high-frequency signal flowing from the first power supply unit 11 to the metal frame 14 via the first impedance control unit 53 is changed. The phase can be changed. Thereby, the high-frequency current flowing through the first antenna element 12 and the high-frequency current flowing through the metal frame 14 can be more preferably set in the same direction so as not to be reversed. Thereby, deterioration of the antenna characteristics of the first antenna element 12 arranged at the position surrounded by the metal frame 14 can be suppressed.

(B) of FIG. 11 is a figure which shows an example of the flow of the high frequency current in the antenna apparatus 5. FIG. As shown in FIG. 11B, the first impedance control unit 53 is configured so that the high-frequency current I0 flowing through the first antenna element 12 and the high-frequency current I2 flowing through the metal frame 14 are in the same direction. The phase of the high frequency signal in the first frequency band may be changed. Thereby, the antenna characteristic of the first antenna element 12 can be improved by allowing the high-frequency current to flow in the same direction in the first antenna element 12 and the metal frame 14. This is because the metal frame 14 is excited in the first frequency band in addition to the first antenna element 12.

The high frequency current flowing through the first antenna element 12 and the high frequency current flowing through the metal frame 14 are preferably controlled by the first impedance control unit 53 so as not to be reversed and more preferably in the same direction. As a method of setting the amount of phase change, a variable phase shifter is used as the first impedance control unit 53, and the phase change is made such that the VSWR is measured while the amount of phase change is changed and the VSWR is reduced. By obtaining the amount experimentally, it can be obtained approximately.

As the phase shifter provided in the first impedance control unit 53, a known phase shifter can be used. For example, a π-type phase shifter (L / C / L type, C / L / C type), T A type phase shifter (L / C / L type, C / L / C type) and the like, and combinations thereof can be used.

(Modification)
Similarly to the ground provided in the antenna device 1, the ground provided in the antenna device 5 is provided on one or more surfaces defined in the antenna device 5, and the first impedance in the one or more surfaces is provided. The ground is preferably removed from the portion facing the control unit 53. Thereby, the 1st impedance control part 53 can adjust an impedance suitably.

Further, the antenna device 5 may include one or more sets of additional antenna elements, power feeding units, and impedance control units. That is, two or more power feeding units may be provided, and each power feeding unit may be connected to the metal frame 14 via an impedance control unit corresponding to each. In this case, it is preferable that the ground is removed from a position facing each impedance control unit on the surface where the ground is provided.

Also in the antenna device 5, similarly to the antenna device 2 according to the second embodiment, a plurality of antenna elements that operate in different frequency bands are connected to the first feeding unit 11, or the first antenna element 12 may operate in a plurality of frequency bands, and the first impedance control unit 53 may change the phase by a suitable amount of change in each frequency band.

Also in the antenna device 5, similarly to the antenna device 3 according to the third embodiment, the metal frame 14 is provided with the slit 36, and the metal frame 14 is configured to be used as an antenna element that operates in the third frequency band. May be. The slits 36 may be provided at a plurality of locations.

[Summary]
The antenna devices (1 to 5) according to the first aspect of the present invention include a first antenna element (12) that operates in a first frequency band, and a first feeding unit (11) connected to the first antenna element. ) And a metal frame (14) disposed so as to surround the first antenna element, and the first power feeding section (11) and the metal frame (14) have impedance in the first frequency band. Is connected via a first impedance control section (13, 23, 53) that adjusts.

According to the above configuration, the first antenna element can be used to transmit and receive high-frequency signals in the first frequency band. Surprisingly, the metal frame arranged so as to surround the first antenna element deteriorates the antenna characteristics of the first antenna element. It can suppress by connecting through the impedance control part which adjusts the impedance in one frequency band. Thereby, deterioration of the antenna characteristics of the first antenna element arranged at the position surrounded by the metal frame can be suppressed.

In the antenna device (1 to 4) according to aspect 2 of the present invention, in the above aspect 1, the first impedance control unit (13, 23) may exhibit high impedance in the first frequency band. .

According to the said structure, a 1st electric power feeding part and a metal frame are connected via a 1st impedance control part which shows a high impedance in a 1st frequency band, A 1st antenna element is by a metal frame. It is possible to suitably suppress the deterioration of the antenna characteristics.

In the antenna device (1 to 4) according to aspect 3 of the present invention, in the above aspect 2, the first impedance control unit (13, 23) is selected from the group consisting of a notch filter, a band elimination filter, and a low-pass filter. One or more of them may be provided.

According to the above configuration, the first impedance control unit showing high impedance in the first frequency band can be suitably realized.

The antenna device (2) according to aspect 4 of the present invention is the above-described

aspect

2 or 3, wherein the antenna device (2) is connected to the first feeding unit (11) and operates in a second frequency band different from the first frequency band. Two antenna elements (22) may be further provided, and the first impedance control unit (23) may further exhibit high impedance in the second frequency band.

According to the above configuration, the second antenna element can be used to transmit and receive high-frequency signals in the second frequency band. At this time, when the first impedance control unit further exhibits high impedance in the second frequency band, it is possible to suppress deterioration of the antenna characteristics of the second antenna element.

In the antenna device (2) according to aspect 5 of the present invention, in the

above aspect

2 or 3, the first antenna element further operates in a second frequency band different from the first frequency band. The impedance control unit (23) may further exhibit high impedance in the second frequency band.

According to the above configuration, a high-frequency signal in the second frequency band can be transmitted and received using the first antenna element. At this time, since the first impedance control unit further exhibits high impedance in the second frequency band, it is possible to suppress deterioration of the antenna characteristics of the first antenna element in the second frequency band.

In the antenna device (2) according to aspect 6 of the present invention, in the

above aspect

4 or 5, the first impedance control unit (23) includes a filter exhibiting high impedance in the first frequency band, and a second frequency band. It may include a configuration in which a filter exhibiting high impedance is connected in series.

According to the above configuration, it is possible to suitably realize the first impedance control unit that exhibits high impedance in the first frequency band and the second frequency band.

In the antenna device (3) according to aspect 7 of the present invention, in the above aspects 2 to 6, the metal frame (14) is provided with a third frequency lower than the first frequency band. A slit (36) for use as an antenna element operating in a band is provided. In the metal frame (14), the slit (36) and a first impedance control unit ( The electrical length of the first portion sandwiched between the connection point (P1) to 13) may be in the range of 1/8 wavelength to 3/8 wavelength in the third frequency band.

According to the above configuration, the metal frame is provided with the slit, and the portion of the metal frame sandwiched between the slit and the connection point to the impedance control unit resonates in the third frequency band. Thereby, the metal frame can be suitably used as an antenna element that operates in the third frequency band.

The antenna device (3) according to aspect 8 of the present invention is the antenna device (3) according to aspect 7, in the second aspect, in the metal frame (14), which is located on the opposite side to the first portion across the connection point (P1). The portion may be grounded via a constant adjustment unit (37) that adjusts the impedance of the metal frame (14).

According to the above configuration, the metal frame can be suitably matched by adjusting the impedances of the first frequency and the third frequency of the metal frame by the constant adjustment unit.

The antenna device (4) according to the ninth aspect of the present invention is the third antenna element (4) in the second to eighth aspects, which is disposed at a position surrounded by the metal frame (14) and operates in the fourth frequency band. 42) and a second feeding part (41) connected to the third antenna element (42), and the second feeding part (41) and the metal frame (14) The second impedance control unit (43) may be configured to exhibit high impedance in the fourth frequency band.

According to the above configuration, the third antenna element can be used to transmit and receive a high frequency signal in the fourth frequency band. At this time, the deterioration of the antenna characteristics of the third antenna element is suppressed by connecting the second feeding unit and the metal frame via the second impedance control unit that exhibits high impedance in the fourth frequency band. can do. Further, the two antennas can be provided by separate power feeding, and the interference between the antennas can be suppressed.

In the antenna device (5) according to the tenth aspect of the present invention, in the first aspect, the first impedance control unit (53) includes a phase shifter that changes the phase in the first frequency band. May be.

According to the above configuration, the first impedance control unit changes the phase in the first frequency band, so that the phase of the high-frequency signal that flows from the first power supply unit to the metal frame via the first impedance control unit. Can be changed. Thereby, it is more preferable that the high-frequency current flowing through the first antenna element and the high-frequency current flowing through the metal frame are in the same direction so as not to be reversed. Thereby, deterioration of the antenna characteristics of the first antenna element arranged at the position surrounded by the metal frame can be suppressed.

In the antenna device (5) according to aspect 11 of the present invention, in the aspect 10, the first impedance control unit (53) includes the high-frequency current flowing through the first antenna element (12) and the metal frame (14). The phase of the high-frequency signal in the first frequency band may be changed so that the high-frequency current flowing in the same direction.

According to the above configuration, the antenna characteristics of the first antenna element can be improved by allowing the high-frequency current to flow in the same direction in the antenna element and the metal frame.

An antenna device (1 to 5) according to aspect 12 of the present invention includes the ground provided on one or more surfaces defined in the antenna device according to any of the above aspects 1 to 11, and the one or more surfaces. The ground (15, 45) may be removed from the portion facing the first impedance control section (13, 23, 53).

According to the above configuration, since the first impedance control unit is prevented from being coupled to the ground, the first impedance control unit can suitably adjust the impedance.

A wireless device according to aspect 13 of the present invention may include the antenna device (1 to 5) according to aspects 1 to 12 and the wireless circuit unit (10) connected to the antenna device. Good.

According to the above configuration, the same effect as that of the antenna device according to one aspect of the present invention can be obtained.

One aspect of the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and the technical means disclosed in different embodiments can be appropriately combined. Such embodiments are also included in the technical scope of the present invention. Furthermore, a new technical feature can be formed by combining the technical means disclosed in each embodiment.

(Example of antenna radiation)
Hereinafter, effects of one embodiment of the present invention will be described in detail with reference to examples. However, this example is for explaining the operation of one embodiment of the present invention, and is not intended to be construed as limiting the scope of the present invention.

In the antenna device in which the antenna element is disposed at a position surrounded by the metal frame, (1) when only the antenna element is fed, (2) when the antenna element and the metal frame are fed, (3) The antenna characteristics were measured for each of the cases configured as in the embodiment.

12 is a cross-sectional view illustrating a schematic configuration of the antenna device used in the example and the comparative example. FIG. 12A illustrates the antenna device 8 according to the comparative example 1, and FIG. 12B illustrates the comparative example 2. The antenna apparatus 9 is shown, (c) shows the antenna apparatus 1 which concerns on Example 1. FIG. As shown in FIG. 12, each antenna device includes a first power feeding unit 11, a first antenna element 12, and a metal frame 14, and a part of a radio device including the antenna device and the radio circuit unit 10. It is configured as. The metal frame 14 is provided with a plurality of slits 36. Further, only the antenna device 1 according to the first embodiment is provided with the first impedance control unit 13.

As Comparative Example 1, as shown in FIG. 12A, the first feeding unit 11 feeds only the first antenna element 12, and the first feeding unit 11 and the metal frame 8 are not connected. In the antenna device 8, the antenna efficiency and the VSWR were measured while changing the operating frequency (the frequency at which the first feeding unit 11 feeds the first antenna element 12) in the range of 5 GHz to 6 GHz.

Further, as Comparative Example 2, as shown in FIG. 12B, in the antenna device 9 in which the first feeding unit 11 feeds power to the first antenna element 12 and the metal frame 8, the operating frequency is 5 GHz to 6 GHz. Antenna efficiency and VSWR were measured while varying in range.

As Example 1, as shown in FIG. 12C, the first feeding unit 11 feeds the first antenna element 12, and the first feeding unit 11 and the metal frame 8 are In the antenna device 1 connected via one impedance control unit 13, the antenna efficiency and the VSWR were measured while changing the operating frequency in the range of 5 GHz to 6 GHz.

As the first impedance control unit 13, a notch filter having a configuration as shown in FIG. 4A, in which the capacitance of the capacitor C1 is 0.4 pF and the inductance of the inductor L1 is 1.5 nH is used.

FIG. 13 shows a through characteristic (attenuation specification) of the first impedance control unit 13 (notch filter). As shown in FIG. 13, the first impedance control unit 13 has the highest through characteristic impedance in the vicinity of 5.2 GHz, which is about −25 dB.

Fig. 14 shows the measurement results of antenna efficiency. FIG. 15 shows the measurement results of VSWR. In the graph, the range surrounded by the vertical dotted line indicates each bandwidth of the Wi-Fi (registered trademark) 5 GHz band (W52 (5150-5250 MHz) / W53 (5250-5350 MHz) / W56 (5470-5725 MHz)). (5150-5725MHz).

In Comparative Example 1 (when only the antenna element was fed), a sufficient value for VSWR was obtained within a certain range, but a low value was shown for antenna efficiency. This is considered to be an influence of being shielded by the metal frame.

In Comparative Example 2 (when the antenna element and the metal frame are fed), a sufficient value for VSWR was not obtained, and the antenna efficiency was lower than that of Comparative Example 1. Thus, when the antenna element and the metal frame are fed, the antenna characteristics are deteriorated as compared with the case where only the antenna element is fed.

In Example 1 (when configured as in the embodiment of the present invention), a sufficient value for VSWR was obtained in a wide band, and the highest value for antenna efficiency was also shown. Thus, according to one embodiment of the present invention, it is considered that the influence of being shielded by the metal frame can be significantly reduced.

In particular, in the vicinity of 5.2 GHz where the through characteristic of the first impedance control unit 13 used in Example 1 is the highest impedance, the antenna characteristic of Example 1 shows the peak efficiency (near 5.25 GHz), It was shown that the through characteristic of the first impedance control unit 13 and the antenna characteristic are generally linked.

Further, even in the vicinity of 5.7 GHz, the antenna characteristics of Example 1 were improved by about 1.5 dB from Comparative Example 1 (antenna element alone). As shown in FIG. 13, the through characteristic of the first impedance control unit 13 in the vicinity of 5.7 GHz is about −8 dB. Therefore, if the through characteristic of the first impedance control unit 13 is −10 dB or less, It was shown that a sufficient improvement effect can be expected.

From the above, it can be seen that the antenna characteristic improves as the through characteristic of the first impedance control unit 13 increases. In the first embodiment, 1.5 nH is used as the value of the inductor L1, but if this value is increased and the capacitor C1 is adjusted to be smaller accordingly, the through characteristics can be made higher impedance, and the antenna characteristics Will be improved.

In addition, in the multiband antenna configuration such as the antenna device 3 shown in FIG. 7, in addition to the antenna element 12, the metal frame 14 antenna is also used as an antenna in the third frequency band lower than the first frequency band (for example, 5 GHz). Make it work. At this time, impedance fluctuation due to the inductor L1 of the first impedance control unit 13 in the metal frame 14 cannot be ignored, and antenna matching adjustment of the metal frame 14 becomes difficult. Therefore, in the multiband antenna configuration such as the antenna device 3 shown in FIG. 7, it is preferable to set the value of the inductor L1 of the first impedance control unit 13 in consideration of these trade-offs.

1-5 Antenna device (radio device)
DESCRIPTION OF SYMBOLS 10 Radio circuit part 11 1st electric power feeding part 12

1st antenna element

13, 23, 53 1st impedance control part 14

Metal frame

15, 45 Ground 22 2nd antenna element 36 Slit 37 Constant adjustment part 41 2nd Feed unit 42 Third antenna element 43 Second impedance control unit P1 Connection point P2 End point C1 to C4 Capacitor L1 to L4 Inductor

Claims

A first antenna element operating in a first frequency band;
A first feeder connected to the first antenna element;
A metal frame arranged so as to surround the first antenna element,
The antenna device, wherein the first power feeding unit and the metal frame are connected via a first impedance control unit that controls impedance in a first frequency band.
The antenna device according to claim 1, wherein the first impedance control unit exhibits high impedance in the first frequency band.
The antenna device according to claim 2, wherein the first impedance control unit includes one or more selected from the group consisting of a notch filter, a band elimination filter, and a low-pass filter.
A second antenna element connected to the first power feeding unit and operating in a second frequency band different from the first frequency band;
The antenna device according to claim 2, wherein the first impedance control unit further exhibits a high impedance in the second frequency band.
The first antenna element further operates in a second frequency band different from the first frequency band,
The antenna device according to claim 2, wherein the first impedance control unit further exhibits a high impedance in the second frequency band.
The first impedance control unit includes a configuration in which a filter showing high impedance in the first frequency band and a filter showing high impedance in the second frequency band are connected in series. The antenna device according to 4 or 5.
The metal frame is provided with a slit for using the metal frame as an antenna element that operates in a third frequency band lower than the first frequency band,
In the metal frame, the electrical length of the first portion sandwiched between the slit and the connection point to the first impedance control unit in the metal frame is 1/8 wavelength or more in the third frequency band. The antenna device according to any one of claims 2 to 6, wherein the antenna device has a range of 8 wavelengths or less.
In the metal frame, a second part located on the opposite side of the first part across the connection point is grounded via a constant adjustment unit that adjusts the impedance of the metal frame. The antenna device according to claim 7.
A third antenna element disposed at a position surrounded by the metal frame and operating in a fourth frequency band;
A second feeding part connected to the third antenna element, and
The second power feeding unit and the metal frame are connected via a second impedance control unit,
The antenna device according to any one of claims 2 to 8, wherein the second impedance control unit exhibits a high impedance in the fourth frequency band.
The antenna device according to claim 1, wherein the first impedance control unit includes a phase shifter that changes a phase in the first frequency band.
The first impedance control unit changes the phase of the high-frequency signal in the first frequency band so that the high-frequency current flowing through the first antenna element and the high-frequency current flowing through the metal frame are in the same direction. The antenna device according to claim 10.
A ground provided on one or more surfaces defined in the antenna device;
The antenna device according to any one of claims 1 to 11, wherein the ground is removed from a portion of the one or more surfaces facing the first impedance control unit.
An antenna device according to any one of claims 1 to 12,
And a wireless circuit unit connected to the antenna device.