JP6710952B2 - Antenna device - Google Patents

Description

The present invention relates to an antenna device.

Conventionally, a first radiating antenna element that is formed substantially parallel to a predetermined first direction and includes a first radiating antenna element that is fed from a first feeding point provided at a first edge of a ground conductor is provided. There is an antenna device provided with one antenna.

The antenna device is formed substantially parallel to a predetermined second direction different from the first direction, and is fed from a second feeding point provided at a second edge of the ground conductor. It further comprises a second antenna comprising two radiating antenna elements.

The antenna device includes a third radiating antenna element that is formed substantially parallel to the second direction and is fed from a third feeding point provided at the second edge of the ground conductor. A fourth radiating antenna element which is formed substantially parallel to the third antenna and which is fed from a fourth feeding point provided at a third edge of the ground conductor. And a fourth antenna provided.

The first and fourth antennas are provided symmetrically with respect to a predetermined line of symmetry on the ground conductor, and the second and third antennas have a predetermined distance between the second and third feeding points. It is characterized in that they are juxtaposed symmetrically with respect to the line of symmetry so as to be separated from each other.

Also, the first antenna includes a first ground antenna element having one end connected to the ground conductor and another end connected to one end of the first radiating antenna element; A first feed antenna element for connecting a point to a predetermined first connection point on the first radiating antenna element, the other end of the first radiating antenna element being an open end This is an inverted F-type antenna.

The second antenna has a second ground antenna element having one end connected to the ground conductor and the other end connected to one end of the second radiating antenna element, and the second feeding point. A second feeding antenna element that connects to a predetermined second connection point on the second radiating antenna element, and the other end of the second radiating antenna element is an open end; It is an F-type antenna.

The third antenna includes a third ground antenna element having one end connected to the ground conductor and the other end connected to one end of the third radiating antenna element; and the third feeding point. A third feeding antenna element for connecting to a predetermined third connection point on the third radiating antenna element, and the other end of the third radiating antenna element is an open end; It is an F-type antenna.

The fourth antenna has a fourth ground antenna element having one end connected to the ground conductor and the other end connected to one end of the fourth radiating antenna element; a fourth feeding point; And a fourth feeding antenna element for connecting to a predetermined fourth connection point on the fourth radiating antenna element, the other end of the fourth radiating antenna element being a fourth inverted F having an open end. Antenna (see, for example, Patent Document 1).

International Publication No. 2013/114840

The conventional antenna device has three antenna elements (a feeding antenna element and a ground antenna element) because each of the first antenna, the second antenna, the third antenna, and the fourth antenna corresponds to three frequency bands. , Radiating antenna element).

In addition, the first antenna, the second antenna, the third antenna, and the fourth antenna are each arranged in a region allocated around the ground conductor (ground plate). Then, in each region, the three antenna elements are arranged along the edge of the ground conductor from one end to the other end with almost no gap.

For this reason, the conventional antenna device has a problem that it is difficult to realize multiband.

Then, it aims at providing the antenna device suitable for multi-band.

An antenna device according to an embodiment of the present invention includes a base plate having an end side, a first line extending from a feeding point located near an intermediate point of both ends of the end side in a direction away from the end side, and A second line extending from the tip of the first line along the edge, and a third line extending from the tip of the second line toward the edge and having the tip connected to the edge. A first antenna element that constructs a loop antenna with a section between a first connection point where the tip of the third line is connected to the one of the end sides, A first antenna element, a second line of the third line and the second line, wherein a total length of the first line, the second line and the third line is a half wavelength at a first communication frequency. A second antenna element extending from the connection point in a direction opposite to the second line, and having a length obtained by subtracting the length of the third line from a quarter wavelength at a second communication frequency, A second antenna element in which the length of the extended section is ⅛ or more of the wavelength at the second communication frequency.

It is possible to provide an antenna device suitable for multi-banding.

It is a figure which shows the antenna device 100 of Embodiment 1. It is a figure which shows the antenna device 100 of Embodiment 1. 5 is a diagram showing frequency characteristics of S11 parameter of the antenna device 100. FIG. FIG. 7 is a diagram showing an antenna device 100A of a first modified example of the first embodiment. It is a figure which shows the frequency characteristic of S11 parameter of antenna device 100A. It is a figure which shows the frequency characteristic of the total efficiency of 100 A of antenna devices. FIG. 10 is a diagram showing a model in which the size of the base plate 50 on the negative side of the X-axis is changed in the antenna device 100A of the first modified example of the first embodiment. It is a figure which shows the frequency characteristic of the S11 parameter in the model of FIG. FIG. 7 is a diagram showing an antenna device 100B of a second modified example of the first embodiment. FIG. 6 is a diagram showing an antenna device 200 according to a second embodiment. 9 is a diagram showing frequency characteristics of S11 parameter of the antenna device 200. FIG. FIG. 9 is a diagram showing an antenna device 200A of a modified example of the second embodiment. It is a figure which shows the antenna device 300 of Embodiment 3. FIG. 9 is a diagram showing frequency characteristics of S11 parameter of the antenna device 300. It is a figure which shows the modification of Embodiment 3. FIG. 16 is a diagram showing frequency characteristics of S11 parameters of the antenna device of the modification of the third embodiment.

Hereinafter, an embodiment to which the antenna device of the present invention is applied will be described.

<Embodiment 1>
1 and 2 are diagrams showing an antenna device 100 according to the first embodiment.

The antenna device 100 includes a ground plane (ground plane) 50 and antenna elements 110 and 120. The antenna device 100 is housed inside a housing of an electronic device having a communication function. In this case, part of the antenna element 110 or 120 may be exposed on the outer surface of the electronic device.

The ground plate 50 is a metal layer that is held at the ground potential, and is a rectangular metal layer having vertices 51, 52, 53, and 54. The base plate 50 is, for example, a metal layer arranged on a surface or an inner layer of a wiring board of FR-4 (Flame Retardant type 4) standard. For example, an electronic element or electronic chip of an electronic device including the antenna device 100 is mounted on the substrate having the base plate 50, and the metal layer 50 is used as a ground potential layer.

In FIG. 1, the metal layers 50 having straight edges between the vertices 51 and 52, between the vertices 52 and 53, between the vertices 53 and 54, and between the vertices 54 and 51 are shown. In some cases, the projections and depressions may not be linear because the projections and depressions are provided in accordance with the internal shape of the housing of the electronic device including the antenna device 100.

In addition, below, the side between the vertices 51 and 52 is called the edge 50A. The side extending from the apex 51 along the Y axis is referred to as an end side 50B. The edge 50B is an example of another edge connected to the edge 50A.

The antenna element 110 has a feeding point 111, bent portions 112 and 113, and a connecting portion 114. The antenna element 110 extends from the feeding point 111 in the positive direction of the Y axis to the bent portion 112, is bent in the negative direction of the X axis at the bent portion 112 and extends to the bent portion 113, and is bent in the negative direction of the Y axis at the folded portion 113. It has been extended to the connection portion 114.

The antenna element 110 is a U-shaped element in XY plan view, and is constructed by, for example, a metal foil such as a copper foil or an aluminum foil or a metal plate such as a copper plate. The antenna element 110 is fixed to a housing of an electronic device including the antenna device 100. The antenna element 110 is an example of a first antenna element.

The line between the feeding point 111 and the bent portion 112 is an example of the first line and is constructed by a thin metal foil or a metal plate parallel to the XY plane. The line between the bent portions 112 and 113 is an example of the second line, and is constructed by a thin metal foil or a metal plate parallel to the XZ plane. The line between the bent part 113 and the connection part 114 is an example of a third line, and is constructed by a thin metal foil or a metal plate parallel to the XY plane.

The feeding point 111 is located in the vicinity of the midpoint 50A1 of the end side 50A while being separated from the midpoint 50A1 of the end side 50A in the Y-axis positive direction. The intermediate point 50A1 is a point located between (intermediate points) the vertices 51 and 52.

In FIG. 1 and FIG. 2, as an example, the midpoint 50A1 has a length up to the apex 51 and a length up to the apex 52 when the length of the end side 50A is equally divided between the apices 51 and 52. The position is about 3:2.

The intermediate point 50A1 is not limited to the position shown in FIGS. 1 and 2, as long as it is located between the vertices 51 and 52 (intermediate point). The position of the intermediate point 50A1 in the X-axis direction is on the side where the antenna elements 110 and 120 are not formed (the X-axis positive direction side from the intermediate point 50A1 in FIGS. 1 and 2) and the communication frequency (resonance) with the antenna elements 110 and 120. The position may be such as to leave a region in which one or more other antenna elements having different frequencies can be arranged.

For example, a core wire of a coaxial cable is connected to the power feeding point 111 and high frequency power is supplied. In this case, the shield wire of the coaxial cable is connected to the intermediate point 50A1, and the intermediate point 50A1 is held at the ground potential.

Note that power may be supplied to the feeding point 111 by a microstrip line, a coplanar line, or the like instead of the core wire of the coaxial cable.

At the bending portion 112, the antenna element 110 extending from the feeding point 111 in the positive direction of the Y axis is bent in the negative direction of the X axis. In the bent portion 113, the antenna element 110 extending from the bent portion 112 in the negative X-axis direction is bent in the negative Y-axis direction.

The connecting portion 114 is a portion where the antenna element 110 extending from the bending portion 113 in the negative direction of the Y axis is connected to the apex 51 of the base plate 50. Therefore, the connection portion 114 is held at the ground potential.

Such an antenna element 110 cooperates with a portion between the apex 51 of the edge 50A of the main plate 50 and the intermediate point 50A1 to construct a loop antenna. The length from the feeding point 111 of the antenna element 110 to the connecting portion 114 via the bent portions 112 and 113 is set to half (λ ₁ /2) of the wavelength λ ₁ of the communication frequency f ₁ .

The antenna element 120 has a connecting portion 121, a bent portion 122, and an open end 123. The connection part 121 is the same part as the bent part 113 of the antenna element 110, and the antenna element 120 is connected to the antenna element 110 at the bent part 113.

The antenna element 120 extends from the connecting portion 121 in the negative direction of the X axis, is bent in the negative direction of the Y axis at the bending portion 122, and extends to the open end 123.

The antenna element 120 is an L-shaped element in XY plan view, and is constructed by, for example, a metal foil such as a copper foil or an aluminum foil or a metal plate such as a copper plate. The antenna element 120 is fixed to a housing or the like of an electronic device including the antenna device 100. The antenna element 120 is an example of a second antenna element.

The line between the connection part 121 and the bent part 122 is constructed by a thin metal foil or a metal plate parallel to the XZ plane. The line between the bent portion 122 and the open end 123 is constructed by a thin metal foil or metal plate parallel to the YZ plane.

Such an antenna element 120 cooperates with a line between the bent portion 113 and the connection portion 114 of the antenna element 110 to construct a monopole antenna. The length from the connecting portion 121 of the antenna element 120 to the open end 123 via the bending portion 122 is from 1/4 (λ ₂ /4) of the wavelength λ ₂ of the communication frequency f2 to the bending portion 113 and the connecting portion 114. It is set to a length less the length of the line between them.

In other words, the length from the connection portion 114 to the open end 123 via the bent portion 113 (connection portion 121) and the bent portion 122 is set to 1/4 (λ ₂ /4) of the wavelength λ ₂ of the communication frequency f2. Has been done.

Further, a point 124 between the bent portion 122 and the open end 123 is a point whose position in the Y-axis direction is the same as that of the apex 51. The area between the point 124 and the open end 123 is an area that overlaps with the main plate 50 in the Y-axis direction. The antenna element 120 obtains an electromagnetic field coupling with the ground plane 50 and adjusts the impedance with the ground plane 50 so that the length of the section between the point 124 and the open end 123 is 1 of the wavelength λ ₂ at the communication frequency f2. The length is set to /8 or more. Therefore, the length of the base plate 50 in the Y-axis direction is also set to be ⅛ or more of the wavelength λ _{2 at} the communication frequency f2.

By configuring the antenna element 120 as described above, the antenna element 120 functions as a monopole antenna in cooperation with the line between the bent portion 113 and the connection portion 114 of the antenna element 110.

FIG. 3 is a diagram showing frequency characteristics of the S11 parameter of the antenna device 100. The frequency characteristic of the S11 parameter shown in FIG. 3 is obtained by electromagnetic field simulation.

Here, as an example, the result when the communication frequency f1 is set to 3 GHz and the communication frequency f2 is set to 4.6 GHz is shown. That is, the length (λ ₁ /2) of the antenna element 110 was set to a half wavelength at 3 GHz in consideration of the wavelength shortening rate and/or the electrical length. Further, the length of the antenna element 120 (λ ₂ /4 minus the length of the line between the bent portion 113 and the connection portion 114) is taken into consideration in terms of the wavelength shortening rate and/or the electrical length. Then, the length was set to 4.6 GHz.

In addition, here, as an example, the evaluation criterion of the value of the S11 parameter is set to −4 dB, and the band of −4 dB or less is evaluated as a communicable area of the antenna device 100.

As shown in FIG. 3, a band having an S11 parameter of -4 dB or less was obtained in a range from about 2.8 GHz around 3 GHz to about 3.2 GHz. This band is a band including the designed communication frequency f1 (3 GHz).

In addition, a band having an S11 parameter of about -3 dB was obtained at around 4.6 GHz. This is higher than the evaluation standard of -4 dB, but it is clear that resonance occurs around 4.6 GHz, and the antenna element 120 is a line between the bent portion 113 of the antenna element 110 and the connection portion 114. We have confirmed that it works as a monopole antenna in cooperation with.

Here, in order to evaluate the characteristics of the antenna device 100 in relation to the wavelength, the case where the communication frequency f1 is set to 3 GHz and the communication frequency f2 is set to 4.6 GHz has been described as an example. When the antenna device 100 is used by setting the communication frequency f1 or f2 to a frequency other than the above, the dimensions of the antenna elements 110 and 120 may be set according to the frequency to be used.

As described above, according to the first embodiment, in the region where the antenna elements 110 and 120 are on the Y axis positive direction side of the end side 50A of the main plate 50, the X axis direction is more negative than the feeding point 111 and the intermediate point 50A1 in the X axis direction. It is located on the side. In other words, in the area on the Y axis positive direction side of the end side 50A of the main plate 50, nothing is arranged on the X axis positive direction side of the feeding point 111 and the intermediate point 50A1 in the X axis direction.

Therefore, in a region on the Y axis positive direction side of the base plate 50 on the Y axis positive direction side, another antenna element having a different communication frequency is provided on the X axis direction from the feeding point 111 and the intermediate point 50A1 to the X axis positive direction side. It is possible to arrange.

Therefore, according to the first embodiment, it is possible to provide the antenna device 100 suitable for multi-banding.

Further, the antenna device 100 according to the first embodiment includes an antenna element 110 that cooperates with the main plate 50 to construct a loop antenna, and an antenna element 120 that cooperates with the antenna element 110 to construct a monopole antenna. In the region on the Y-axis positive direction side of the end side 50A, it is arranged on the X-axis negative direction side of the feeding point 111 and the intermediate point 50A1 in the X-axis direction.

The antenna element 110 has an extremely long length because it has a length (λ ₁ /2) that is half the wavelength λ ₁ of the communication frequency f ₁ . Further, when the antenna device 100 is used in a smartphone terminal or a mobile phone terminal, the size of the space on the Y axis positive direction side of the edge 50A of the main plate 50 is the X axis direction, the Y axis direction, and the Z axis. Very limited in direction.

The antenna device 100 according to the first embodiment has a very long length in the space on the X-axis negative direction side of the feeding point 111 and the intermediate point 50A1 in the X-axis direction in the space with the limited size. It houses the antenna element 110.

As described above, according to the first embodiment, the antenna element 110 having a very long length, which is half the wavelength λ ₁ of the communication frequency f ₁ (λ ₁ /2), is housed in the limited space. At the same time, it is possible to provide the antenna device 100 suitable for multi-band.

Next, an antenna device 100A of a modified example of the first embodiment will be described.

FIG. 4 is a diagram showing an antenna device 100A according to a first modified example of the first embodiment.

The antenna device 100A includes a main plate 50 and antenna elements 110 and 120A. The antenna device 100A has a configuration in which the position of the antenna element 110 of the antenna device 100 shown in FIGS. 1 and 2 is moved to the X-axis positive direction side, and the antenna element 120 is replaced with the antenna element 120A.

Therefore, the configurations of the base plate 50 and the antenna element 110 are similar to those of the base plate 50 and the antenna element 110 of the antenna device 100 shown in FIGS. 1 and 2. Hereinafter, differences from the antenna device 100 shown in FIGS. 1 and 2 will be described.

The antenna element 110 shown in FIG. 4 is moved to the X-axis positive direction side by the length of the antenna element 120A in the X-axis direction as compared with the antenna element 110 shown in FIGS. 1 and 2. Here, the point where the connection point 114 of the antenna element 110 is connected to the edge 50A of the ground plane 50 is referred to as a point 50A2.

The antenna element 120A has a connecting portion 121A and an open end 123A. The connecting portion 121A is the same portion as the bent portion 113 of the antenna element 110, and the antenna element 120A is connected to the antenna element 110 at the bent portion 113.

The antenna element 120A extends from the connection portion 121A in the negative direction of the X axis to the open end 123A. The position of the open end 123A in the X-axis direction is equal to the position of the end side 50B.

The antenna element 120A is a linear element in XY plan view, and is constructed by, for example, a metal foil such as a copper foil or an aluminum foil or a metal plate such as a copper plate. The antenna element 120A is fixed to a housing of an electronic device including the antenna device 100A. The antenna element 120A is an example of a second antenna element.

The line between the connecting portion 121A and the open end 123A is constructed of a thin metal foil or a metal plate parallel to the XZ plane.

Such an antenna element 120A cooperates with a line between the bent portion 113 and the connection portion 114 of the antenna element 110 to construct a monopole antenna. The length from the connection portion 121A of the antenna element 120A to the open end 123A is 1/4 (λ ₂ /4) of the wavelength λ ₂ of the communication frequency f2 from the length of the line between the bent portion 113 and the connection portion 114. It is set to the length less the length.

In other words, the length from the connection portion 114 to the open end 123A via the bent portion 113 (connection portion 121A) is set to 1/4 (λ ₂ /4) of the wavelength λ ₂ of the communication frequency f2.

Further, the section from the connecting portion 121A of the antenna element 120A to the open end 123A (the entire section of the antenna element 120A) is a section that overlaps with the main plate 50 in the X-axis direction. The antenna element 120A obtains an electromagnetic field coupling with the ground plane 50 and adjusts the impedance with the ground plane 50, so that the length of the section from the connection portion 121A to the open end 123A is 1 of the wavelength λ ₂ at the communication frequency f2. The length is set to /8 or more. Therefore, the length in the X-axis direction between the point 50A2 of the main plate 50 and the apex 51 is also set to be ⅛ or more of the wavelength λ _{2 at} the communication frequency f2. In FIG. 4, the length of the section from the connecting portion 121A to the open end 123A is equal to the length in the X-axis direction between the point 50A2 and the apex 51.

By configuring the antenna element 120A as described above, the antenna element 120A functions as a monopole antenna in cooperation with the line between the bent portion 113 and the connection portion 114 of the antenna element 110.

Here, in the modification of the first embodiment, the sizes of the base plate 50 and the antenna elements 110 and 120A are as follows. Here, as an example, the sizes of the antenna elements 110 and 120A when the communication frequency f1 is set to 3 GHz and the communication frequency f2 is set to 4.1 GHz are shown.

The length of the base plate 50 in the X-axis direction is 83 mm, the length in the Y-axis direction is 151 mm, and the thickness in the Z-axis direction is 3.5 mm.

The length between the feeding point 111 and the bent portion 112 of the antenna element 110 is 5.50 mm, the length between the bent portions 112 and 113 is 44.25 mm, and the length between the bent portion 113 and the connection portion 114 is 5. It is 0.50 mm. Therefore, the length from the feeding point 111 of the antenna element 110 to the connecting portion 114 via the bent portions 112 and 113 is 55.25 mm. The width of the antenna element 110 in the Z-axis direction is 1 mm.

The length between the connecting portion 121A and the open end 123A of the antenna element 120A is 13.50 mm. Therefore, the length from the connecting portion 114 functioning as a monopole antenna to the open end 123A through the bent portion 113 (connecting portion 121A) is 19 mm. The width of the antenna element 120A in the Z-axis direction is 1 mm.

The length from the bent portion 112 to the open end 123A via the bent portion 113 (connecting portion 121A) is 57.75 mm.

Here, in order to evaluate the characteristics of the antenna device 100A in relation to the wavelength, as an example, a case where the communication frequency f1 is set to 3 GHz and the communication frequency f2 is set to 4.1 GHz will be described. When the communication frequency f1 or f2 is set to a frequency other than the above and the antenna device 100A is used, the dimensions of the antenna elements 110 and 120A may be set according to the frequency to be used.

FIG. 5 is a diagram showing frequency characteristics of the S11 parameter of the antenna device 100A. The frequency characteristic of the S11 parameter shown in FIG. 5 is obtained by electromagnetic field simulation.

Here, as an example, the result when the communication frequency f1 is set to 3 GHz and the communication frequency f2 is set to 4.1 GHz is shown. That is, the length (λ ₁ /2) of the antenna element 110 was set to a half wavelength at 3 GHz in consideration of the wavelength shortening rate and/or the electrical length. Further, the length of the antenna element 120A (the length obtained by subtracting the length of the line between the bent portion 113 and the connection portion 114 from λ ₂ /4) is taken into consideration in the wavelength shortening rate and/or the electrical length. Then, the length was set to 4.1 GHz.

Further, here, as an example, the evaluation criterion of the value of the S11 parameter is set to −4 dB, and the band equal to or lower than −4 dB is evaluated as a communicable area of the antenna device 100A.

As shown in FIG. 5, a band having an S11 parameter of -4 dB or less was obtained in the range of about 2.8 GHz to about 3.3 GHz around 3 GHz. This band is a band including the designed communication frequency f1 (3 GHz).

In addition, a band having an S11 parameter of -3 dB or less was obtained in the range of about 4.0 GHz to about 4.2 GHz around 4.1 GHz. This is higher than the evaluation standard of -4 dB, but it is clear that resonance occurs around 4.1 GHz, and the antenna element 120A is a line between the bent portion 113 of the antenna element 110 and the connection portion 114. We have confirmed that it works as a monopole antenna in cooperation with.

FIG. 6 is a diagram showing frequency characteristics of total efficiency of the antenna device 100A. The total efficiency represents the characteristics of the electronic device to which the antenna device 100A is attached, and includes the matching loss between the feeding point 111 and the impedance of the antenna device 100A. The frequency characteristic of total efficiency shown in FIG. 6 is obtained by an electromagnetic field simulation.

As shown in FIG. 6, peaks are obtained at communication frequencies f1 (3 GHz) and f2 (4.1 GHz), and it can be confirmed that communication can be performed at communication frequencies f1 (3 GHz) and f2 (4.1 GHz). It was

As described above, according to the modification of the first embodiment, in the region where the antenna elements 110 and 120A are on the Y axis positive direction side of the end side 50A of the main plate 50, the antenna elements 110 and 120A are more X than the feeding point 111 and the intermediate point 50A1 in the X axis direction. It is arranged on the negative side of the shaft. In other words, in the area on the Y axis positive direction side of the end side 50A of the main plate 50, nothing is arranged on the X axis positive direction side of the feeding point 111 and the intermediate point 50A1 in the X axis direction.

Therefore, in a region on the Y axis positive direction side of the base plate 50 on the Y axis positive direction side, another antenna element having a different communication frequency is provided on the X axis direction from the feeding point 111 and the intermediate point 50A1 to the X axis positive direction side. It is possible to arrange.

Therefore, according to the modified example of the first embodiment, it is possible to provide the antenna device 100A suitable for multi-banding.

Here, the frequency characteristics of the S11 parameter when the size of the main plate 50 on the negative side of the X axis is changed will be described with reference to FIGS. 7 and 8.

FIG. 7 is a diagram showing a model in which the size of the base plate 50 on the negative side in the X-axis direction is changed in the antenna device 100A of the first modified example of the first embodiment. FIG. 8 is a diagram showing frequency characteristics of the S11 parameter in the model of FIG. The frequency characteristic of the S11 parameter shown in FIG. 8 is obtained by electromagnetic field simulation.

Here, in the electromagnetic field simulation, the size of the ground plane 50 of the antenna device 100A is changed as shown in FIG. The size change is to reduce the size of the main plate 50 by shifting the position of the edge 50B on the negative X-axis side of the main plate 50 toward the positive X-axis side.

In FIG. 7, the apex 51 is shown at the same position as the apex 51 of the main plate 50 shown in FIG. The position of the edge 50B shown in FIG. 7 is equal to the position of the edge 50B shown in FIG. The amount of displacement of the position of the edge 50B in the positive direction of the X axis is represented as displacement amount w.

The frequency characteristic of the S11 parameter was obtained by electromagnetic field simulation while displacing the position of the edge 50B in the positive direction of the X axis to reduce the size of the ground plane 50.

FIG. 8 shows frequency characteristics of the S11 parameter when the displacement amount w is 0 mm, 4.5 mm, 7.5 mm, 10.5 mm, and 12 mm.

When the displacement amount w is 0 mm, it has the same configuration as the antenna device 100A shown in FIG. 4, and the position of the open end 123A in the X-axis direction is equal to the position of the end side 50B. Further, since the length between the connecting portion 121A and the open end 123A is 13.50 mm, when the displacement amount w is 12 mm, the end side 50B extends in the X axis direction from the connecting portion 121A to the X axis negative direction. It will be at a position of 1.5 mm on the side.

Even if the displacement amount w was changed, no great change was observed in the value of the S11 parameter at the communication frequency f1. From this, it was found that reducing the size of the ground plane 50 on the negative side of the X-axis has almost no effect on the radiation characteristics of the antenna element 110.

On the other hand, when the displacement amount w was changed, the value of the S11 parameter at the communication frequency f2 changed significantly. As the displacement amount w increased, the value of the S11 parameter increased. When the displacement amount w is 0 mm and 4.5 mm, a value of -3 dB or less is obtained at the communication frequency f2 (4.1 GHz), but when the displacement amount w is 7.5 mm or more, a value greater than -3 dB. Became. Further, FIG. 8 shows the S11 parameter when the displacement amount w is 0 mm, 4.5 mm, 7.5 mm, 10.5 mm, and 12 mm, but when the displacement amount w is larger than 4.5 mm, it is more than −3 dB. It was also confirmed that

Therefore, it was found that when the displacement amount w is 4.5 mm or less, the radiation characteristic of the antenna element 120A becomes a level that can be used for communication. Further, when the displacement amount w is 4.5 mm, the distance from the connecting portion 121A to the end side 50B in the X-axis direction is 9 mm. 9 mm corresponds to ⅛ of the wavelength λ _{2 at} the communication frequency f2 (4.1 GHz).

Therefore, in order to obtain good radiation characteristics of the antenna element 120A, the length of the overlapping section in the X-axis direction between the antenna element 120A and the ground plane 50 is 1/8 of the wavelength λ _{2 at} the communication frequency f2 (4.1 GHz). It turned out that it was necessary to be above.

In the antenna device 100 shown in FIGS. 1 and 2, the antenna element 120 has a section that overlaps the edge 50B of the base plate 50 in the Y-axis direction. The overlapping section is between the point 124 and the open end 123. Like the antenna element 120 of the antenna device 100 shown in FIGS. 1 and 2, when the front end side having the open end 123 is bent in the Y-axis direction, if there is a section that overlaps with the main plate 50 in the Y-axis direction. Often, the length of the overlapping section is ⅛ or more of the wavelength λ _{2 at} the communication frequency f2.

FIG. 9 is a diagram showing an antenna device 100B according to a second modification of the first embodiment.

The antenna device 100B is obtained by bending the bent portion 122 of the antenna element 120 of the antenna device 100 shown in FIG. 1 into a curved shape in XY plan view. The antenna device 100B includes a base plate 50 and antenna elements 110 and 120B.

The antenna element 120B extends from the connection portion 121 in the negative direction of the X-axis, is curved in the negative direction of the Y-axis at the curved portion 122B, and extends to the open end 123. Other configurations of the antenna device 100B are similar to those of the antenna device 100 shown in FIG.

The antenna element 120B thus curvedly bent by the curved portion 122B may be exposed on the outer surface of the electronic device. In this case, the antenna element 120B and the section of the antenna element 110 between the bent portions 112 and 113 may be exposed on the outer surface of the electronic device. The curved shape of the curved portion 122B may be matched to the design of the outer surface of the electronic device.

<Second Embodiment>
FIG. 10 is a diagram showing the antenna device 200 according to the second embodiment.

The antenna device 200 includes a main plate 50 and antenna elements 110, 120, and 230. The antenna device 200 has a configuration in which an antenna element 230 is added to the antenna device 100 (see FIGS. 1 and 2) of the first embodiment. Since other configurations are similar to those of the antenna device 100 of the first embodiment, the same components are designated by the same reference numerals and the description thereof will be omitted.

When the antenna device 200 is housed inside the housing of the electronic device, a part of the antenna element 230 is exposed on the outer surface of the electronic device in addition to the part of the antenna element 110 or 120. Good.

The antenna element 230 has a connection portion 231, a bent portion 232, and an open end 233.

The connecting portion 231 is the same portion as the bent portion 112 of the antenna element 110, and is the portion of the bent portion 112 that is connected to the antenna element 110.

The antenna element 230 extends from the connection portion 231 to the X-axis positive direction side, is bent at the bending portion 232, and extends to the Y-axis negative direction side to the open end 233.

The antenna element 230 is an L-shaped element in XY plan view, and is constructed by, for example, a metal foil such as a copper foil or an aluminum foil or a metal plate such as a copper plate. The antenna element 230 is fixed to a housing of an electronic device including the antenna device 200. The antenna element 230 is an example of a third antenna element.

The line between the connection portion 231 and the bent portion 232 is constructed by a thin metal foil or a metal plate parallel to the XZ plane. The line between the bent portion 232 and the open end 233 is constructed by a thin metal foil or a metal plate parallel to the YZ plane.

Such an antenna element 230 cooperates with a line between the feeding point 111 and the bent portion 112 of the antenna element 110 to construct a monopole antenna. The length from the connection portion 231 of the antenna element 230 to the open end 233 through the bent portion 232, a quarter of the wavelength lambda ₃ of the communication frequency f3 (λ _3/4), the bent portion 112 and the feeding point 111 It is set to a length less the length of the line between them.

In other words, the length from the feeding point 111 to the open end 233 through the bent portion 112 (connecting unit 231) and the bent portion 232, set to 1/4 (lambda _3/4) of the wavelength lambda ₃ of the communication frequency f3 Has been done.

By configuring the antenna element 230 as described above, the antenna element 230 functions as a monopole antenna in cooperation with the line between the feeding point 111 of the antenna element 110 and the bent portion 112.

FIG. 11 is a diagram showing frequency characteristics of the S11 parameter of the antenna device 200. The frequency characteristic of the S11 parameter shown in FIG. 11 is obtained by electromagnetic field simulation.

Here, as an example, the result when the communication frequency f1 is set to 3 GHz, the communication frequency f2 is set to 4.6 GHz, and the communication frequency f3 is set to 1.5 GHz is shown. That is, the length (λ ₁ /2) of the antenna element 110 was set to a half wavelength at 3 GHz in consideration of the wavelength shortening rate and/or the electrical length. Further, the length of the antenna element 120 (λ ₂ /4 minus the length of the line between the bent portion 113 and the connection portion 114) is taken into consideration in terms of the wavelength shortening rate and/or the electrical length. Then, the length was set to 4.6 GHz.

Moreover, (the length obtained by subtracting the length of the line between the lambda _3/4 and bent portion 112 from the feeding point 111) the length of the antenna element 230, shortening of the wavelength, and / or, taking into account the electrical length Then, the length at 1.5 GHz was set.

In addition, here, as an example, the evaluation criterion of the value of the S11 parameter is set to −4 dB, and the band of −4 dB or less is evaluated as a communicable area of the antenna device 200.

As shown in FIG. 11, a band having an S11 parameter of -4 dB or less was obtained in the range of about 2.85 GHz around 3 GHz to about 3.3 GHz. This band is a band including the designed communication frequency f1 (3 GHz).

In addition, a band having an S11 parameter of -3 dB or less was obtained in the range of about 4.5 GHz to about 4.8 GHz around 4.6 GHz. This is higher than the evaluation standard of -4 dB, but it is clear that resonance occurs around 4.6 GHz, and the antenna element 120 is a line between the bent portion 113 of the antenna element 110 and the connection portion 114. We have confirmed that it works as a monopole antenna in cooperation with.

In addition, a band having an S11 parameter of -3 dB or less was obtained in the range of about 1.45 GHz to about 1.7 GHz around 1.5 GHz. This is higher than the evaluation standard of -4 dB, but it is clear that resonance occurs around 1.5 GHz, and the antenna element 230 is a line between the feeding point 111 of the antenna element 110 and the bent portion 112. We have confirmed that it works as a monopole antenna in cooperation with.

Here, in order to evaluate the characteristics of the antenna device 200 in relation to the wavelength, as an example, the communication frequency f1 is set to 3 GHz, the communication frequency f2 is set to 4.6 GHz, and the communication frequency f3 is set to 1. The case of setting to 5 GHz has been described. When the antenna device 200 is used by setting the communication frequency f1, f2, or f3 to a frequency other than the above frequencies, the dimensions of the antenna elements 110, 120, and 230 may be set according to the frequency to be used.

As described above, according to the second embodiment, in the region on the Y axis positive direction side of the edge 50A of the main plate 50, from the feeding point 111 and the intermediate point 50A1 in which the antenna elements 110 and 120 are not arranged in the X axis direction. Also, the antenna element 230 is arranged in the region on the X-axis positive direction side.

Then, the antenna element 230 functions as a monopole antenna in cooperation with the line between the feeding point 111 of the antenna element 110 and the bent portion 112.

Therefore, according to the second embodiment, it is possible to provide the antenna device 200 compatible with three bands and suitable for multibanding.

In the above description, the antenna element 230 extends from the connection portion 231 in the direction (X-axis positive direction) opposite to the line between the bent portions 112 and 113 of the antenna element 110. However, the antenna element 230 (the line between the connection part 231 and the bent part 232) is not limited to the X-axis positive direction, and may extend in a direction different from the line between the bent parts 112 and 113. .. For example, it may extend from the connecting portion 231 in the positive direction of the Y-axis, or may extend in the positive direction of the Y-axis and then bend and extend in the positive direction of the X-axis.

FIG. 12 is a diagram showing an antenna device 200A of a modified example of the second embodiment.

In the antenna device 200A, the antenna element 120 of the antenna device 200 shown in FIG. 10 is replaced with the antenna element 120B shown in FIG. 9, and the bent portion 232 of the antenna element 230 of the antenna device 200 shown in FIG. 10 is curved in an XY plan view. It is curved. The antenna device 200A includes a main plate 50 and antenna elements 110, 120B, and 230A.

The antenna element 230A extends from the connection portion 231 in the positive direction of the X axis, is curved in the negative direction of the Y axis at the curved portion 232A, and extends to the open end 233. Other configurations of the antenna device 200A are similar to those of the antenna device 200 shown in FIG.

The antenna element 230A bent in the curved portion 232B in this manner may be exposed on the outer surface of the electronic device. In this case, the antenna element 230A, the antenna element 120B, and the section of the antenna element 110 between the bent portions 112 and 113 may be exposed on the outer surface of the electronic device. The curved shape of the curved portions 232A and 122B may be matched to the design of the outer surface of the electronic device.

<Third Embodiment>
FIG. 13 is a diagram showing the antenna device 300 according to the third embodiment.

The antenna device 300 includes a base plate 50, antenna elements 110, 120, and 230, and a parasitic element 340. The antenna device 300 has a configuration in which a parasitic element 340 is added to the antenna device 200 (see FIG. 10) of the second embodiment. Since other configurations are the same as those of the antenna device 200 of the second embodiment, the same components are designated by the same reference numerals and the description thereof will be omitted.

When the antenna device 300 is housed inside the housing of the electronic device, part of the parasitic element 340 is provided on the outer surface of the electronic device in addition to part of the antenna element 110, 120, or 230. It may be exposed.

The parasitic element 340 has a connection portion 341, bent portions 342, 343, 344, and an open end 345.

The connecting portion 341 is connected to the apex 52 of the main plate 50. Therefore, the connection portion 341 is the ground end.

The parasitic element 340 extends from the connecting portion 341 to the Y-axis positive direction side, is bent at the bending portion 342 to extend to the X-axis negative direction side, and is bent at the bending portion 343 to extend to the Y-axis negative direction side. The bent portion 344 is bent and extends to the X-axis positive direction side up to the open end 345.

The line between the bent portion 342 and the bent portion 343 is arranged close to and parallel to the line between the connection portion 231 of the element 230 and the bent portion 232. The line between the bent portion 342 and the bent portion 343 is arranged close to the line between the connection portion 231 and the bent portion 232 so that electric power is supplied by electromagnetic field coupling.

The parasitic element 340 is constructed by, for example, a metal foil such as a copper foil or an aluminum foil or a metal plate such as a copper plate. The parasitic element 340 is fixed to the housing of the electronic device including the antenna device 300.

The parasitic element 340 is constructed by a thin metal foil or a metal plate parallel to the XY plane from the connection portion 341 to the open end 345 via the bent portions 342, 343, and 344, for example. The line between the connection part 341 and the bent part 342 is an example of the fourth line, and the line between the bent part 342 and the bent part 343 is an example of the fifth line, and the bent part 343 to the bent part The line extending from 344 to the open end 345 is an example of the sixth line.

In the parasitic element 340, the line between the bent portion 342 and the bent portion 343 receives electric power from the element 230 by electromagnetic coupling with the line between the connection portion 231 and the bent portion 232. Functions as a pole antenna.

The length from the connection portion 341 of the parasitic element 340 to the open end 345 via the bent portions 342, 343, 344 is set to ¼ (λ ₄ /4) length of the wavelength λ ₄ of the communication frequency f4. ..

By configuring the parasitic element 340 as described above, the parasitic element 340 is electromagnetically coupled to the antenna element 230 and functions as a monopole antenna.

FIG. 14 is a diagram showing frequency characteristics of the S11 parameter of the antenna device 300. The frequency characteristic of the S11 parameter shown in FIG. 14 is obtained by electromagnetic field simulation.

Here, as an example, the result when the communication frequency f1 is set to 3 GHz, the communication frequency f2 is set to 4.6 GHz, the communication frequency f3 is set to 1.5 GHz, and the communication frequency f4 is set to 2.5 GHz Indicates.

That is, the lengths of the antenna elements 110, 120 and 230 are the same as those described in the second embodiment. In addition, the length (λ ₄ /4) of the parasitic element 340 is set to the length of a quarter wavelength of the wavelength at 2.5 GHz in consideration of the wavelength shortening rate and/or the electrical length.

In addition, here, as an example, the evaluation criterion of the value of the S11 parameter is set to −4 dB, and the band equal to or lower than −4 dB is evaluated as a communicable region of the antenna device 300.

As shown in FIG. 14, a band having an S11 parameter of -4 dB or less was obtained in the range of about 2.85 GHz around 3 GHz to about 3.3 GHz. This band is a band including the designed communication frequency f1 (3 GHz).

In addition, a band having an S11 parameter of -3 dB or less was obtained in the range of about 4.5 GHz to about 4.8 GHz around 4.6 GHz. This is higher than the evaluation standard of -4 dB, but it is clear that resonance occurs around 4.6 GHz, and the antenna element 120 is a line between the bent portion 113 of the antenna element 110 and the connection portion 114. We have confirmed that it works as a monopole antenna in cooperation with.

In addition, a band having an S11 parameter of -1 dB or less was obtained in the range of about 1.2 GHz to about 1.4 GHz. This is also higher than the evaluation standard of -4 dB, but it is clear that resonance occurs around 1.2 GHz, and the antenna element 230 is a line between the feeding point 111 of the antenna element 110 and the bent portion 112. We have confirmed that it works as a monopole antenna in cooperation with.

It should be noted that the resonance frequency f2 is slightly shifted to the low frequency side as compared with the element 230 of the second embodiment because of the influence of electromagnetic field coupling with the parasitic element 340 and the arrangement of the parasitic element 340. It is considered that the influence of the impedance fluctuation occurred.

Here, in order to evaluate the characteristics of the antenna device 300 in relation to the wavelength, as an example, the communication frequency f1 is set to 3 GHz, the communication frequency f2 is set to 4.6 GHz, and the communication frequency f3 is set to 1. The case where the frequency is set to 5 GHz and the communication frequency f4 is set to 2.5 GHz has been described. When the communication frequency f1, f2, f3, or f4 is set to a frequency other than the above and the antenna device 300 is used, the dimensions of the antenna elements 110, 120, and 230 and the parasitic element 340 are adjusted according to the frequency to be used. Should be set.

As described above, according to the third embodiment, in the region on the Y axis positive direction side of the edge 50A of the main plate 50, from the feeding point 111 and the intermediate point 50A1 in which the antenna elements 110 and 120 are not arranged in the X axis direction. Also, the antenna element 230 and the parasitic element 340 are arranged in the region on the X-axis positive direction side.

The parasitic element 340 is electromagnetically coupled to the antenna element 230 and functions as a monopole antenna.

Therefore, according to the third embodiment, it is possible to provide the antenna device 300 that supports four bands and that is suitable for multibanding.

Note that, here, a modification of the third embodiment will be described with reference to FIG.

FIG. 15 is a diagram showing a modification of the third embodiment. Here, a modification in which the matching circuits 350, 360, and 370 are attached to the antenna device 300 illustrated in FIG. 13 to improve the impedance matching between the antenna elements 110, 120, and 230 and the parasitic element 340 will be described.

In FIG. 15, the antenna elements 110, 120, and 230 and the parasitic element 340 are simplified and shown as one block, and the feeding point 111, the connecting portion 114, and the connecting portion 341 are shown.

The matching circuit 350 has capacitors 351 and 352 and a coil 353. The capacitors 351 and 352 are connected in series between the circuit 380 such as an amplifier that supplies power to the antenna device 100 and the power supply point 111. The coil 353 branches from between the capacitors 351 and 352 and is connected to the midpoint 50A1. Here, the capacitances of the capacitors 351 and 352 were set to 2.6 pF, and the inductance of the coil 353 was set to 3.5 nH.

As the matching circuit 360, a 1 nH coil was used. The matching circuit 360 is connected in series between the connection portion 114 and the point 50A2.

As the matching circuit 370, a 3.7 pF capacitor was used. The matching circuit 360 is connected in series between the connecting portion 341 and the apex 52.

FIG. 16 is a diagram showing frequency characteristics of the S11 parameter of the antenna device of the modification of the third embodiment. The frequency characteristic of the S11 parameter shown in FIG. 16 is obtained by electromagnetic field simulation.

As shown in FIG. 16, a band in which the S11 parameter was −4 dB or less was obtained in the range of about 2.7 GHz to about 3.2 GHz.

Further, a band having an S11 parameter of -4 dB or less is obtained in a range of about 4.2 GHz to about 4.4 GHz, and the antenna element 120 cooperates with a line between the bent portion 113 of the antenna element 110 and the connection portion 114. Then, it was confirmed that it functions as a monopole antenna.

In addition, a band with an S11 parameter of -4 dB or less is obtained in the range of about 1.3 GHz to about 1.35 GHz, and the monopole cooperates with the line between the feeding point 111 of the antenna element 110 and the bent portion 112. It was confirmed that it could function as an antenna.

In addition, it was confirmed that the band with the S11 parameter of -4 dB or less was obtained in the range of about 2.4 GHz to about 2.7 GHz, and the parasitic element 340 electromagnetically coupled with the antenna element 230 to function as a monopole antenna. did it.

The frequency characteristic of the S11 parameter shown in FIG. 16 is obtained by adding a filter, a coil, and a capacitor to the antenna device 300 shown in FIG. 13, and measures the lengths of the antenna elements 110, 120 and 230 and the parasitic element 340. It is the simulation result obtained in order to see the reduction degree of the value of the S11 parameter without optimization.

Therefore, if the lengths of the antenna elements 110, 120 and 230 and the parasitic element 340 are optimized, the communication frequency f1 (3 GHz), the communication frequency f2 (4.6 GHz), the communication frequency f3 (1.5 GHz). At the communication frequency f4 (2.5 GHz), it is considered that the value of the S11 parameter of -4 dB or less can be obtained.

Note that the matching circuits 350, 360, and 370 are merely examples, and the configuration and the capacitance value and the inductance value of the matching element are not limited thereto, and a capacitor may be used instead of the coil, and a coil may be used instead of the capacitor. May be.

Although the antenna device according to the exemplary embodiment of the present invention has been described above, the present invention is not limited to the specifically disclosed embodiment, without departing from the scope of the claims, Various modifications and changes are possible.
Regarding the above embodiment, the following additional notes will be disclosed.
(Appendix 1)
A ground plane with edges,
A first line extending from a feeding point located near the first point on the edge in a direction away from the edge, and a second line extending from a tip of the first line along the edge. And a third line extending from the tip of the second line toward the edge, the tip being connected to the edge, and the third line is provided on the edge of the edge. A first antenna element for constructing a loop antenna with a section between a first connection point to which the tip is connected and the first point, the first line, the second line, and the third line A first antenna element, the total length of which is a half wavelength at the first communication frequency;
A length obtained by extending in a direction opposite to the second line from a second connection point where the third line and the second line are connected, and subtracting the length of the third line from a quarter wavelength at the second communication frequency. A second antenna element having a height, the length of a section extending along the ground plane being ⅛ or more of a wavelength at the second communication frequency, and a second antenna element.
(Appendix 2)
The section having a length of ⅛ or more of the wavelength at the second communication frequency of the second antenna element is along the edge of the ground plane or another edge connected to the edge. The antenna device according to appendix 1.
(Appendix 3)
Appendix 1 or 2, wherein the second antenna element has a curved portion that curves in a curved shape from the extension direction of the end side of the ground plane toward the extension direction of the other side connected to the end side. Antenna device.
(Appendix 4)
It extends from a third connection point between the first line and the second line in a direction different from the second line, and has a length obtained by subtracting the length of the first line from a quarter wavelength at a third communication frequency. The antenna device according to any one of appendices 1 to 3, further including a third antenna element.
(Appendix 5)
A fourth line extending from a point closer to the third antenna element than the first point on the end side in a direction away from the end side, and a third antenna from the tip of the fourth line. The antenna device according to Appendix 4, further comprising a parasitic element having a fifth line extending along the element toward the first line and having a length of a quarter wavelength at a fourth communication frequency.
(Appendix 6)
The parasitic element further includes a sixth line that is folded back from the tip of the fifth line toward the fourth line, and has a total length of the fourth line, the fifth line, and the sixth line. The antenna device according to attachment 5, which has a quarter wavelength at the fourth communication frequency.
(Appendix 7)
7. The antenna device according to appendix 5 or 6, wherein the parasitic element is electromagnetically coupled to the third antenna element.

100, 100A, 100B Antenna device 50 Base plate 51, 52, 53, 54 Vertices 110, 120 Antenna element 111 Feeding point 112, 113 Bent part 114 Connection part 121 Connection part 122 Bent part 123 Open end 100A Antenna device 120A, 120B Antenna element 121A connection part 122 bent part 122B curved part 123A open end 200, 200A antenna device 230 antenna element 231 connection part 232 bend part 233 open end 300 antenna device 340 parasitic element 341 connection part 342, 343, 344 bend part 345 open end

Claims (7)

A ground plane with edges,
A first line extending from a feeding point located near the first point on the edge in a direction away from the edge, and a second line extending from a tip of the first line along the edge. And a third line extending from the tip of the second line toward the edge, the tip being connected to the edge, and the third line is provided on the edge of the edge. A first antenna element for constructing a loop antenna with a section between a first connection point to which the tip is connected and the first point, the first line, the second line, and the third line A first antenna element, the total length of which is a half wavelength at the first communication frequency;
A length obtained by extending in a direction opposite to the second line from a second connection point where the third line and the second line are connected, and subtracting the length of the third line from a quarter wavelength at the second communication frequency. A second antenna element having a height, the length of a section extending along the ground plane being ⅛ or more of a wavelength at the second communication frequency, and a second antenna element. The section having a length of ⅛ or more of the wavelength at the second communication frequency of the second antenna element is along the edge of the ground plane or another edge connected to the edge. The antenna device according to claim 1, wherein The said 2nd antenna element has a curved part which curves in a curved shape toward the extension direction of the other side connected to the said edge side from the extension direction of the said edge side of the said ground plane. The antenna device described. It extends from a third connection point between the first line and the second line in a direction different from the second line, and has a length obtained by subtracting the length of the first line from a quarter wavelength at a third communication frequency. The antenna device according to claim 1, further comprising a third antenna element. A fourth line extending from a point closer to the third antenna element than the first point on the end side in a direction away from the end side, and a third antenna from the tip of the fourth line. The antenna device according to claim 4, further comprising: a parasitic element having a fifth line extending toward the first line along an element and having a length of a quarter wavelength at a fourth communication frequency. The parasitic element further includes a sixth line that is folded back from the tip of the fifth line toward the fourth line, and has a total length of the fourth line, the fifth line, and the sixth line. The antenna device according to claim 5, wherein the antenna device has a quarter wavelength at the fourth communication frequency. The antenna device according to claim 5, wherein the parasitic element is electromagnetically coupled to the third antenna element.

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