JP7315694B2 - Antenna device and wireless communication device - Google Patents

Description

The present invention relates to antenna devices and wireless communication devices.

Antenna devices that can resonate at a plurality of frequencies have been proposed (see Patent Documents 1 to 3, for example).

JP 2009-111999 A JP 2018-148533 A Japanese Patent Publication No. 2008-503972

In the antenna device, adding a frequency that can resonate is realized by adding a parasitic element. However, if a parasitic element is added each time a resonant frequency is added, it becomes difficult to miniaturize the antenna device, and it also becomes difficult to miniaturize the wireless communication device in which the antenna device is mounted.

An object of one aspect of the disclosed technology is to provide a smaller antenna device that supports multiple frequencies and a wireless communication device that implements the antenna device.

One aspect of the disclosed technology is exemplified by the following antenna device. a grounded ground substrate having a feeding point; a first plate-shaped conductor element having one end electrically connected to the grounded area of the ground substrate and parallel to the ground substrate; a second plate-shaped conductor element having one end electrically connected to the feeding point and parallel to the ground substrate; a third plate-shaped conductor element arranged in parallel with the second conductor element with a gap; , wherein the gap capacitively couples the second conductor element and the third conductor element with respect to a radio wave whose wavelength is four times the length of a path from the feeding point to the third conductor element via the second conductor element.

The disclosed technology is smaller and can support multiple frequencies.

FIG. 1 is a diagram illustrating an example of an antenna device according to an embodiment. FIG. 2 is a first diagram schematically showing the resonance state of the antenna device according to the embodiment. FIG. 3 is a second diagram schematically showing the resonance state of the antenna device according to the embodiment. FIG. 4 is a third diagram schematically showing the resonance state of the antenna device according to the embodiment. FIG. 5 is a fourth diagram schematically showing the resonance state of the antenna device according to the embodiment. FIG. 6 is a diagram illustrating reflection coefficients of the antenna device according to the embodiment. FIG. 7 is a diagram illustrating a configuration in which the antenna device according to the embodiment is mounted on a smart phone; FIG. 8 is a first diagram illustrating an example of a configuration of an antenna device implemented by a smartphone according to an implementation example; FIG. 9 is a second diagram illustrating an example of the configuration of the antenna device mounted on the smartphone according to the mounting example. FIG. 10 is a third diagram illustrating an example of the configuration of the antenna device mounted on the smartphone according to the mounting example. FIG. 11 is a fourth diagram illustrating an example of the configuration of the antenna device mounted on the smartphone according to the mounting example. FIG. 12 is a diagram illustrating reflection coefficients of an antenna device in an implementation example. FIG. 13 is a diagram illustrating another example of mounting the antenna according to the embodiment on a smartphone; FIG. 14 is a diagram showing an example of a matching circuit inserted in a gap of an antenna device. FIG. 15 is a diagram illustrating parameters used in the simulation. FIG. 16 is a diagram illustrating simulation results. FIG. 17 is a diagram showing an example of an antenna device according to a first modified example. FIG. 18 is a first diagram schematically showing the resonance state of the antenna device according to the first modified example. FIG. 19 is a second diagram schematically showing the resonance state of the antenna device according to the first modified example. FIG. 20 is a third diagram schematically showing the resonance state of the antenna device according to the first modified example. FIG. 21 is a fourth diagram schematically showing the resonance state of the antenna device according to the first modified example. FIG. 22 is a fifth diagram schematically showing the resonance state of the antenna device according to the first modified example. FIG. 23 is a diagram showing an example of an antenna device according to a second modified example. FIG. 24 is a diagram schematically showing the resonance state of the antenna device according to the second modified example. FIG. 25 is a diagram showing an example of a configuration in which a chip component is arranged between the second conductor element and the third conductor element in the second modified example. FIG. 26 is a diagram showing an example of an antenna device according to a third modified example. FIG. 27 is a diagram illustrating a state in which the second conductor element and the third conductor element are removed in the antenna device according to the third modification. FIG. 28 is a diagram illustrating the radiation efficiency of the antenna device in the third modified example when each chip component interposed between the first conductor element and the ground substrate is open and short-circuited.

<Embodiment>
Embodiments will be described below. The configuration of the embodiment shown below is an example, and the disclosed technology is not limited to the configuration of the embodiment. An antenna device according to an embodiment includes:
A ground substrate having a feeding point and grounded;
a plate-shaped first conductor element having one end electrically connected to a grounded area of the ground substrate and parallel to the ground substrate;
a plate-shaped second conductor element having one end electrically connected to the feeding point and parallel to the ground substrate;
a plate-like third conductor element arranged side by side with the second conductor element with a gap therebetween;
a connecting portion that electrically connects the other end of the first conductor element and the third conductor element,
The gap capacitively couples the second conductor element and the third conductor element with respect to an electric wave whose wavelength is four times the length of the path from the feeding point to the third conductor element via the second conductor element.

In the antenna device according to the embodiment, the first conductor element and the ground substrate are electrically connected, and the first conductor element and the third conductor element are electrically connected. Therefore, for the first radio wave whose wavelength is four times the path length from the ground substrate to the third conductor element via the first conductor element, the antenna device can operate as a monopole antenna from the ground substrate to the third conductor element via the first conductor element.

Furthermore, in the antenna device according to the embodiment, a gap is provided between the second conductor element and the third conductor element. The distance of the gap capacitively couples the second conductor element and the third conductor element with respect to the second radio wave whose wavelength is four times the length of the path from the feeding point to the third conductor element via the second conductor element. Therefore, the antenna device according to the embodiment can operate as a monopole antenna extending from the feeding point to the third conductor element via the second conductor element with respect to the second radio wave. The antenna device according to the embodiment can operate as a monopole antenna from the feeding point to the second conductor element for the third radio wave whose one wavelength is four times the path length from the feeding point to the second conductor element.

Furthermore, the antenna device according to the embodiment can operate as a loop antenna extending from the feeding point to the ground substrate via the second conductor element, the third conductor element, and the first conductor element for the fourth radio wave whose path length is one wavelength from the feeding point to the ground substrate via the second conductor element, the third conductor element, and the first conductor element. Since the antenna device according to this embodiment has two parasitic elements, the second conductor element and the third conductor element, it can resonate with radio waves of four frequencies from the first radio wave to the fourth radio wave. That is, since the antenna device according to the embodiment can operate at more frequencies than the number of provided parasitic elements, the size of the antenna device can be easily reduced while supporting a plurality of frequencies.

An antenna device according to an embodiment may have the following features. The feeding point is provided on one surface of the ground substrate, and the first conductor element is electrically connected to the other surface of the ground substrate. With such characteristics, the present antenna device can arrange the first conductor element on the other surface side of the ground substrate, and arrange the second conductor element and the third conductor element on one surface side of the ground substrate.

An antenna device according to an embodiment may have the following features. A matching circuit is provided in the gap for capacitively coupling the second conductor element and the third conductor element with respect to an electric wave whose wavelength is four times the length of a path from the feeding point to the third conductor element via the second conductor element. By using the matching circuit, it is possible to suppress a decrease in sensitivity of the antenna device when the antenna device is mounted on a wireless communication device such as a smart phone. Also, the matching circuit may be a parallel circuit of a capacitor and an inductor, and may include chip components.

The present embodiment may be a wireless communication device in which the antenna device described above is mounted. Wireless communication devices are, for example, smartphones, feature phones, tablet computers, wearable computers, and the like. Also, the first conductor element may be formed in a partial area of a metal exterior frame surrounding the side surface of the wireless communication device. By forming the first conductor element in a partial region of the exterior frame, the wireless communication device can be made more compact.

Embodiments will be further described below with reference to the drawings. FIG. 1 is a diagram illustrating an example of an antenna device according to an embodiment. An antenna device 1 illustrated in FIG. Hereinafter, in this specification, the first conductor element 11 side is the bottom, the second conductor element 12 side is the top, the right direction in FIG. 1 is right, and the left direction in FIG. 1 is left.

The ground board 2 is formed in a plate shape. A front surface 21 and a rear surface 22 of the ground substrate 2 are grounded. A feeding point 221 is provided on the rear surface 22 of the ground substrate 2 formed in a plate shape.

The first conductor element 11 is an element formed by forming a conductor such as metal into a plate shape and arranged on the surface 21 side of the ground substrate 2 . The first conductor element 11 is parallel to the ground substrate 2 . One end 111 of the first conductor element 11 is electrically connected to the surface 21 of the ground substrate 2 via the first connection conductor 31 .

The second conductor element 12 is an element formed by forming a conductor such as metal into a plate shape and arranged on the rear surface 22 side of the ground substrate 2 . The second conductor element 12 is parallel to the ground substrate 2 . That is, in the example of FIG. 1, the first conductor element 11 and the second conductor element 12 are parallel. One end 121 of the second conductor element 12 is electrically connected to a feeding point 221 provided on the rear surface 22 of the ground substrate 2 .

The third conductor element 13 is an element formed by forming a conductor such as metal into a plate shape and arranged on the rear surface 22 side of the ground substrate 2 . The third conductor element 13 is parallel to the ground substrate 2 . That is, in the example of FIG. 1, the first conductor element 11 and the third conductor element 13 are parallel. Further, the longitudinal central axis of the third conductor element 13 and the longitudinal central axis of the second conductor element 12 substantially coincide. A gap 4 is formed between one end 131 of the third conductor element 13 and the other end 122 of the second conductor element 12 . The third conductor element 13 is electrically connected to the other end 112 of the first conductor element 11 via the second connection conductor 32 at the connection portion 133 between the one end 131 and the other end 132 . Although the third conductor element 13 protrudes further to the right from the connection portion 133 in FIG. That is, in the third conductor element 13 , the connecting portion 133 may coincide with the other end 132 of the third conductor element 13 .

Here, the distance of the gap 4 (distance between the other end 122 of the second conductor element 12 and the one end 131 of the third conductor element 13) is a distance that insulates the second conductor element 12 and the third conductor element 13 against radio waves having a wavelength four times the length from the feeding point 221 to the other end 122 of the second conductor element 12. Further, the distance of the gap 4 is a distance that capacitively couples the second conductor element 12 and the third conductor element 13 with respect to an electric wave having a wavelength four times longer than the length from the feeding point 221 to the other end 132 of the third conductor element 12 through the second conductor element 12.

2 to 5 are diagrams schematically showing resonance states of the antenna device according to the embodiment. FIG. 2 illustrates a state in which the antenna 101 resonates. Antenna 101 includes first connection conductor 31 , first conductor element 11 , second connection conductor 32 and third conductor element 13 from connection portion 133 to other end 132 . That is, the antenna 101 resonates with a first radio wave whose wavelength is four times the length of the first connection conductor 31, the first conductor element 11, the second connection conductor 32, and the connection portion 133 to the other end 132 of the third conductor element 13 (illustrated as a dotted arrow L1 in FIG. 2). In other words, the antenna 101 is a monopole antenna that resonates at the quarter wavelength of the first radio wave.

FIG. 3 illustrates a state in which the antenna 102 resonates. Antenna 102 includes feed point 221 , second conductor element 12 and third conductor element 13 . Here, the distance of the gap 4 is the distance that capacitively couples the second conductor element 12 and the third conductor element 13 with respect to a radio wave having a wavelength that is four times or more the length from the feeding point 221 through the second conductor element 12 to the other end 132 of the third conductor element 13 (illustrated as a dotted arrow L2 in FIG. 3). Therefore, the antenna 102 resonates with the second radio wave whose wavelength is four times the length from the feed point 221 to the other end 132 of the third conductor element 13 via the second conductor element 12 . In other words, the antenna 102 is a monopole antenna that resonates at the quarter wavelength of the second radio wave.

FIG. 4 illustrates a state in which the antenna 103 resonates. Antenna 103 includes feed point 221 and second conductor element 12 . Here, the distance of the gap 4 is a length that insulates the second conductor element 12 and the third conductor element 13 from the radio wave having a wavelength four times the length from the feeding point 221 to the other end 122 of the second conductor element 12 (illustrated as a dotted arrow L3 in FIG. 4). Therefore, the antenna 103 resonates with the third radio wave whose wavelength is four times the length from the feeding point 221 to the other end 122 of the second conductor element 12 . In other words, the antenna 103 is a monopole antenna that resonates at the quarter wavelength of the third radio wave.

FIG. 5 illustrates a state in which the antenna 104 resonates. Antenna 104 includes feeding point 221 , second conductor element 12 , one end 131 of third conductor element 13 to connection portion 133 , second connection conductor 32 , first conductor element 11 and first connection conductor 31 . As described above, the gap 4 is a distance that capacitively couples the second conductor element 12 and the third conductor element 13 with respect to a radio wave having a wavelength that is four times or more the length from the feed point 221 to the other end 132 of the third conductor element 13 via the second conductor element 12. Therefore, the antenna 104 resonates with a fourth radio wave whose wavelength is the length from the feeding point 221 to the first end 131 of the second conductor element 12 and the third conductor element 13, the connection portion 133, the second connection conductor 32, the first conductor element 11, and the first connection conductor 31 to the surface 21 of the ground substrate 2 (illustrated as a dotted arrow L4 in FIG. 5). Here, the position where the arrows of the dotted line arrow L4 face each other (for example, the gap 4) is the node of the waveform that resonates in the antenna 104 (the position where the current is weak), and the intermediate portion between the nodes (for example, the feeding point 221) is the antinode of the waveform that resonates in the antenna 104 (the position where the strong current is generated). In other words, the antenna 104 is a loop antenna that resonates at one wavelength of the fourth radio wave.

FIG. 6 is a diagram illustrating reflection coefficients of the antenna device according to the embodiment. In FIG. 6, the vertical axis exemplifies the reflection coefficient (|S1, 1|), and the horizontal axis exemplifies the frequency. As illustrated in FIG. 6, it can be understood that the antenna device 1 exhibits suitable antenna performance at the frequency f1 of the first radio wave, the frequency f2 of the second radio wave, the frequency f3 of the third radio wave, and the frequency f4 of the third radio wave.

<Action and effect of the embodiment>
In the antenna device 1 according to the embodiment, the gap 4 is provided between the second conductor element 12 and the third conductor element 13 . The distance of the gap 4 is set to a distance that insulates the second conductor element 12 and the third conductor element 13 against radio waves having a wavelength four times the antenna length of the antenna 103, and capacitively couples the second conductor element 12 and the third conductor element 13 against radio waves having a wavelength four times the antenna length of the antenna 102. The antenna device 1 having such a configuration can resonate with four frequencies of a first radio wave, a second radio wave, a third radio wave, and a fourth radio wave. In a conventional antenna device, the number of parasitic elements is increased as the frequency at which resonance is possible is increased. Therefore, in order to be able to resonate at four frequencies, for example, one feeding element and three parasitic elements are provided. According to this embodiment, one feeding element (second conductor element 12) and two parasitic elements (first conductor element 11 and third conductor element 13) can resonate at four frequencies. That is, according to this embodiment, it is possible to realize an antenna device that can resonate at a greater number of frequencies with a smaller number of elements than the conventional one. That is, the antenna device 1 according to this embodiment can realize a smaller antenna that can resonate at a plurality of frequencies.

<Example of implementation>
The antenna device 1 according to the embodiment can be mounted on various devices. FIG. 7 is a diagram illustrating a configuration in which the antenna device according to the embodiment is mounted on a smart phone; FIG. 7 illustrates a state in which the cover on the front side of smartphone 500 is opened. Smartphone 500 is formed in a plate shape and has a predetermined thickness. A metal frame 51 surrounds the side surface of the smartphone 500 formed in a plate shape. A base substrate 3 on which various electronic components are mounted is provided in a region surrounded by the metal frame 51 . The side surface of the base substrate 3 facing the metal frame 51 is grounded, for example.

Smartphone 500 is a portable wireless communication device that includes a central processing unit (CPU), memory, and the like. In smartphone 500, antenna device 1 is provided, for example, within an area surrounded by ellipse R1. 8 to 11 are diagrams illustrating an example of the configuration of the antenna device mounted on the smartphone according to the mounting example. FIG. 8 illustrates a state in which the front cover of the smartphone 500 is opened. FIG. 9 illustrates a state in which the second conductor element 12, the third conductor element 13, and the substrate 53 for Laser Direct Structuring (LDS) are removed. 10 is a sectional view taken along the line A--A of FIG. 8, and FIG. 11 is a sectional view taken along the line BB of FIG.

As illustrated in FIG. 8 , in the antenna device 1 mounted on the smartphone 500 , a partial area of the metal frame 51 is used as the first conductor element 11 . In the metal frame 51, the area used as the first conductor element 11 and other areas are insulated from each other by, for example, providing a slit 51a. The second conductor element 12 and the third conductor element 13 are formed in a thin plate shape by LDS on the LDS substrate 53 . Further, as illustrated in FIG. 9, a feeding point 221 is provided on the ground substrate 2 .

As illustrated in FIG. 10, the ground substrate 2 is provided on the base substrate 3, for example. The ground substrate 2 is grounded by being electrically connected to the base substrate 3 . The ground substrate 2 and the base substrate 3 may be formed integrally or may be formed as separate members as long as they share grounding. The LDS substrate 53 is provided parallel to the ground substrate 2 separately from the ground substrate 2 and the base substrate 3 .

As illustrated in FIG. 11 , the second connection conductor 32 and the third conductor element 13 are connected via vias 54 provided in the LDS substrate 53 . Since a part of the metal frame 51 is used as the first conductor element 11, the first conductor element 11, the second conductor element 12, and the third conductor element 13 are arranged side by side in the horizontal direction in FIG. In smartphone 500 , by using metal frame 51 as first conductor element 11 , the number of parts of antenna device 1 in smartphone 500 can be reduced.

FIG. 12 is a diagram illustrating reflection coefficients of an antenna device in an implementation example. In FIG. 12, the vertical axis exemplifies the reflection coefficient (|S1, 1|), and the horizontal axis exemplifies the frequency. As illustrated in FIG. 12 , the antenna device 1 mounted on the smartphone 500 exhibits preferable antenna performance at 1.5 GHz (triangular number 1 in the figure), 2.4 GHz (triangular number 2 in the figure), 3.5 GHz (triangular number 3 in the figure), and 5.5 GHz (triangular number 4 in the figure).

In the mounting example described above, the metal frame 51 surrounding the sides of the smartphone 500 is also used as the first conductor element 11. However, when mounting the antenna device 1 on the smartphone 500, the metal frame 51 may not be used as an antenna. FIG. 13 is a diagram illustrating another example of mounting the antenna according to the embodiment on a smartphone; FIG. 13 is an example of a diagram of the configuration of another example in which the antenna according to the embodiment is mounted on a smartphone, viewed from the -Y direction. In FIG. 13, the second conductor element 12 is provided on the front side (+Z side) of the smartphone 500, and the first conductor element 11 is provided on the rear side (−Z side). That is, the first conductor element 11, the second conductor element 12, and the third conductor element 13 are arranged in the thickness direction. With such a configuration, the antenna device 1 can be accommodated within the metal frame 51 of the smartphone 500 .

<Matching circuit>
When mounting the antenna device 1 on the smartphone 500 , for example, a screw hole is provided in the third conductor element 13 to fix the antenna device 1 in the smartphone 500 , and the antenna device 1 is fixed to the smartphone 500 with a screw. If the screw holes are provided, it is conceivable that the sensitivity of the antenna device 1 is lowered. In view of this, consideration will be given to suppressing the decrease in sensitivity of the antenna device 1 by providing a matching circuit in the gap 4 between the second conductor element 12 and the third conductor element 13 .

FIG. 14 is a diagram showing an example of a matching circuit inserted in a gap of an antenna device. A matching circuit 800 illustrated in FIG. 14 has one end connected to the other end 122 of the second conductor element 12 and the other end connected to one end 131 of the third conductor element 13 . In the matching circuit 800, a capacitor C0, a parallel circuit including an inductor L1 and a capacitor C1, and a parallel circuit including an inductor L2 and a capacitor C2 are connected in series from the other end 122 of the second conductor element 12 toward one end 131 of the third conductor element 13.

In order to verify the effect of the matching circuit 800, a simulation was performed and will be described. In this simulation, a copper plate with a length and width of 150 mm is used as the ground substrate 2 . The length of the second conductor element 12 is assumed to be 10 mm, and the length of the third conductor element 13 is assumed to be 30 mm. Let the distance between the second conductor element 12 and the first conductor element 11 and the distance between the third conductor element 13 and the first conductor element 11 be 5 mm. The distance of the gap 4 between the second conductor element 12 and the third conductor element 13 was changed, and the capacitance of the capacitors C0, C1 and C2 and the inductance of the inductors L1 and L2 of the matching circuit 800 were changed.

FIG. 15 is a diagram illustrating parameters used in the simulation. In FIG. 15, "gap" indicates the distance of the gap 4 (unit: mm). "C0" indicates the capacitance (unit: pF) of the capacitor C0. "L1" indicates the inductance (unit: nH) of inductor L1. "C1" indicates the capacitance (unit: pF) of the capacitor C1. "L2" indicates the inductance (unit: nH) of inductor L2. "C2" indicates the capacitance (unit: pF) of the capacitor C2. "Number" is a number that uniquely identifies each set of parameters.

FIG. 16 is a diagram illustrating simulation results. FIG. 16 illustrates the total efficiency of the antenna device 1 when the combinations of parameters numbered 1 to 5 illustrated in FIG. 15 are applied. The vertical axis of FIG. 16 indicates total efficiency (dB), and the horizontal axis indicates frequency (GHz). When confirming the total efficiency illustrated in FIG. 16 for each frequency of 1.5 GHz, 2.4 GHz, 3.5 GHz, and 5.5 GHz used in (LTE) and fifth generation (for example, millimeter waves) in wireless communication, it can be understood that the antenna device 1 can exhibit a total efficiency close to that in the case where screw holes are not provided by adopting the combination of parameters of number 5.

<First modification>
The antenna device 1 according to the embodiment can be variously modified. FIG. 17 is a diagram showing an example of an antenna device according to a first modified example. FIG. 17 is a side view of the antenna device 1a according to the first modification. The antenna device 1a differs from the antenna device 1 according to the embodiment in that the ground substrate 2 includes the ground substrate 2a and the ground portion 2b, and the first conductor element 11 is grounded by the connecting conductor 31a and the ground portion 2b.

The ground substrate 2 a is a substrate parallel to the first conductor element 11 , the second conductor element 12 and the third conductor element 13 . The ground substrate 2a is formed, for example, in a square shape of 200 mm in length and width. In the antenna device 1 according to the embodiment, the first conductor element 11 is arranged on the front surface 21 side of the ground substrate 2 , and the second conductor element 12 and the third conductor element 13 are arranged on the rear surface 22 side. In the antenna device 1a according to the first modification, all of the first conductor element 11, the second conductor element 12 and the third conductor element 13 are arranged on the surface 21a side of the ground substrate 2a.

A columnar ground portion 2b is erected on the surface 21a of the ground substrate 2a. A feeding point 221 is provided at the tip of the ground portion 2b. In the antenna device 1a, the first conductor element 11 is grounded by being electrically connected to the side surface of the ground portion 2b. The first conductor element 11 is also grounded by electrically connecting the connection conductor 31a to the surface 21 of the ground substrate 2a at the connection portion 113 located between the one end 111 and the other end 112 of the first conductor element 11.

18 to 22 are diagrams schematically showing resonance states of the antenna device according to the first modified example. FIG. 18 illustrates a state in which the antenna 201 resonates. Antenna 201 includes first conductor element 11 , second connection conductor 32 and third conductor element 13 from connection portion 133 to other end 132 . That is, the antenna 201 resonates with the first radio wave whose wavelength is four times the length of the first conductor element 11, the second connection conductor 32, and the connection portion 133 to the other end 132 of the third conductor element 13 (illustrated as a dotted arrow L11 in FIG. 18). In other words, the antenna 201 is a monopole antenna that resonates at the quarter wavelength of the first radio wave.

FIG. 19 illustrates a state in which the antenna 202 resonates. Antenna 202 includes feed point 221 , second conductor element 12 and third conductor element 13 . Antenna 202 resonates with a second radio wave whose wavelength is four times the length from feeding point 221 through second conductor element 12 to the other end 132 of third conductor element 13 (illustrated as dotted arrow L12 in FIG. 19). In other words, the antenna 202 is a monopole antenna that resonates at the quarter wavelength of the second radio wave.

FIG. 20 illustrates a state in which the antenna 203 resonates. Antenna 203 includes feed point 221 and second conductor element 12 . Here, the distance of the gap 4 is a length that insulates the second conductor element 12 and the third conductor element 13 from the radio wave having a wavelength four times the length from the feeding point 221 to the other end 122 of the second conductor element 12 (illustrated as a dotted arrow L13 in FIG. 20). Therefore, the antenna 203 resonates with the third radio wave whose wavelength is four times the length from the feeding point 221 to the other end 122 of the second conductor element 12 . In other words, the antenna 203 is a monopole antenna that resonates at the quarter wavelength of the third radio wave.

FIG. 21 illustrates a state in which the antenna 204 resonates. Antenna 204 includes feed point 221, second conductor element 12, one end 131 of third conductor element 13 to connection portion 133, second connection conductor 32, first conductor element 11, and ground portion 2b. Antenna 204 resonates with a fourth radio wave having a wavelength of a length (illustrated as a dotted arrow L14 in FIG. 21) returning from feeding point 221 to feeding point 221 from one end 131 of second conductor element 12 and third conductor element 13 through connection portion 133, second connection conductor 32, first conductor element 11, and ground portion 2b. The positions of the nodes and antinodes of the resonating waveform in the antenna 104 are the same as those of the antenna 104 illustrated in FIG. In other words, the antenna 204 is a loop antenna that resonates at one wavelength of the fourth radio wave.

FIG. 22 illustrates a state in which the antenna 205 resonates. Antenna 205 includes connection conductor 31 a and connection portion 113 to other end 112 of first conductor element 11 . Therefore, the antenna 205 resonates with a fifth radio wave whose wavelength is the length of the connection conductor 31a, the connection portion 113, and the other end 112 of the first conductor element 11 (illustrated as a dotted arrow L15 in FIG. 22). In other words, the antenna 205 is a monopole antenna that resonates at the 1/4 wavelength of the fifth radio wave.

In the first modified example, by grounding the first conductor element 11 with the ground portion 2b and the connection conductor 31a, the fifth radio wave can also be resonated.

<Second modification>
FIG. 23 is a diagram showing an example of an antenna device according to a second modified example. The antenna device 1b according to the second modification differs from the antenna device 1 according to the embodiment in that the connection conductor 32 is connected not to the middle portion of the third conductor element 13 but to the end portion on the other end 132 side.

FIG. 24 is a diagram schematically showing the resonance state of the antenna device according to the second modified example. FIG. 24 illustrates a state in which the antenna 301 resonates. Antenna 201 includes first connection conductor 31 , first conductor element 11 , and second connection conductor 32 . That is, the antenna 301 resonates with the eleventh radio wave whose wavelength is four times the length of the first connection conductor 31, the first conductor element 11, the second connection conductor 32, and the connection portion 133 to the other end 132 of the third conductor element 13 (illustrated as a dotted arrow L21 in FIG. 24). In other words, the antenna 201 is a monopole antenna that resonates at the quarter wavelength of the 11th radio wave. In the second modification, as described above, the connection conductor 32 is connected to the end of the third conductor element 13 on the other end 132 side, so the length of the dotted arrow L21 is shorter than that of the dotted arrow L1. That is, the eleventh radio wave with which the antenna 301 of the antenna device 1b according to the second modification resonates has a shorter wavelength than the first radio wave with which the antenna 101 of the antenna device 1 according to the embodiment resonates.

The configuration of the antenna device 1b is the same as that of the antenna device 1 according to the embodiment except that the connection conductor 32 is connected to the end of the third conductor element 13 on the other end 132 side. Therefore, the antenna device 1b can also resonate with the second, third and fourth radio waves. In the antenna device 1b according to the second modification, a partial region of the metal frame 51 of the smartphone 500 can be used as the first conductor element 11 as in the mounting example described above.

FIG. 25 is a diagram showing an example of a configuration in which a chip component is arranged between the second conductor element and the third conductor element in the second modified example. The chip component 41 is, for example, a chip resistor or a chip capacitor. As illustrated in FIG. 25, a chip component 41 such as a chip resistor or a chip capacitor may be inserted into the gap 4 .

<Third modification>
FIG. 26 is a diagram showing an example of an antenna device according to a third modified example. Antenna device 1c according to the third modification is provided in an area surrounded by ellipse R1 of smartphone 500 illustrated in FIG. 7, similarly to the above implementation example. FIG. 26 is an example of an enlarged view of the area surrounded by ellipse R1 in FIG. The antenna device 1 c uses a partial area of the metal frame 51 as the first conductor element 11 .

FIG. 27 is a diagram illustrating a state in which the second conductor element and the third conductor element are removed in the antenna device according to the third modification. As can be understood by referring to FIG. 27, the first conductor element 11 is grounded by being electrically connected to the side surface of the ground substrate 2 by the first connection conductor 31 and the chip component 41a at the end on the one end 111 side. The first conductor element 11 is grounded by being electrically connected to the side surface of the ground substrate 2 by the first connection conductor 31a and the chip component 41b on the other end 112 side of the first connection conductor 31. FIG.

FIG. 28 is a diagram illustrating the radiation efficiency of the antenna device in the third modified example when each chip component interposed between the first conductor element and the ground is open and short-circuited. In FIG. 28, the vertical axis indicates radiation efficiency (dB) and the horizontal axis indicates frequency (GHz). In addition, in the legend of FIG. 28, "a" indicates the chip component 41a and "b" indicates the chip component 41b. As can be understood by referring to FIG. 28, by appropriately selecting open or short circuit for each of the chip components 41a and 41b, the frequency of the radio wave that resonates the antenna device 1c can be changed.

The embodiments and modifications described above can be combined as appropriate.

Reference Signs List 1, 1a, 1b, 1c Antenna device 2 Ground substrate 211 Feeding point 3 Base substrate 11 First conductor element 12 Second conductor element 13 Third conductor element 4 Gap 41, 41a, 41b Chip part 101, 102, 103, 104, 201, 202, 203, 204, 205 Antenna 500 Smartphone 51 Metal Frame 800 Matching circuit

Claims (7)

A ground substrate having a feeding point and grounded;
a plate-shaped first conductor element having one end electrically connected to a grounded area of the ground substrate and parallel to the ground substrate;
a plate-shaped second conductor element having one end electrically connected to the feeding point and parallel to the ground substrate;
a plate-like third conductor element arranged side by side with the second conductor element with a gap therebetween;
a connecting portion that electrically connects the other end of the first conductor element and the third conductor element,
The gap capacitively couples the second conductor element and the third conductor element with respect to a radio wave whose wavelength is four times the length of a path from the feeding point to the third conductor element via the second conductor element,
antenna device. The feeding point is provided on one surface of the ground substrate,
the first conductor element is electrically connected to the other surface of the ground substrate;
The antenna device according to claim 1. A matching circuit that capacitively couples the second conductor element and the third conductor element with respect to a radio wave whose wavelength is four times the length of a path from the feeding point to the third conductor element through the second conductor element is provided in the gap.
The antenna device according to claim 1 or 2. The matching circuit includes a parallel circuit of a capacitor and an inductor,
The antenna device according to claim 3. the matching circuit includes a chip component,
The antenna device according to claim 3 or 4. Mounting the antenna device according to any one of claims 1 to 5,
wireless communication device. A side surface of the wireless communication device is surrounded by a metal exterior frame,
wherein the first conductor element is formed in a partial region of the exterior frame;
The radio communication device according to claim 6.

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