This application is based on and claims priority under 35 U.S.C. § 119 to Japanese Patent Application 2021-183246, filed on Nov. 10, 2021, the entire content of which is incorporated herein by reference.
This disclosure relates to an antenna device.
In related art, an antenna device is used for transmission and reception of radio waves. Techniques related to such an antenna device include, for example, those disclosed in JP 2009-225068A (Reference 1), JP 2016-116016A (Reference 2) and WO 2017/138800 (Reference 3).
Reference 1 discloses a circularly polarized composite monopole antenna. The circularly polarized composite monopole antenna includes a ground plate formed of a plate-shaped conductor, and the ground plate is provided with a power feeding element and a parasitic element formed by bending in an inverted L shape. The power feeding element and the parasitic element are erected from the ground plate by allowing a rising side of the power feeding element and a rising side of the parasitic element to pass through a through hole formed in a dielectric on the ground plate.
Reference 2 discloses a wide-band circularly polarized wave antenna. The wide-band circularly polarized wave antenna is implemented such that a first antenna element and a second antenna element both having a trapezoidal shape are arranged point-symmetrically with respect to a power feeding portion.
Reference 3 discloses a monopole antenna. The monopole antenna includes a circular disk-shaped coplanar waveguide transmission line.
In the technique disclosed in Reference 1, since the power feeding element and the parasitic element are formed in a state of being erected from the ground plate via the dielectric, a three-dimensional shape is formed. Therefore, the antenna device may not be used when there is a height limit in a region where the antenna device is disposed. Since the technique disclosed in Reference 2 is a so-called parallel antenna device, a pair of antenna elements are required. Therefore, an area occupied by the antenna device increases. As described above, the techniques disclosed in References 1 and 2 have room for improvement in reducing a size of the antenna device.
Polarized radio waves include, for example, horizontally polarized waves, vertically polarized waves, and circularly polarized waves. The technique disclosed in Reference 3 is a technique related to the monopole antenna, and thus can be used only for transmission and reception of one of the vertically polarized radio waves and the horizontally polarized radio waves. Therefore, the technique disclosed in Reference 3 cannot be used for transmission and reception of the circularly polarized radio waves.
A need thus exists for an antenna device which is not susceptible to the drawback mentioned above.
A characteristic configuration of an antenna device according to this disclosure is an antenna device including: a ground portion including a linear portion connecting a first point and a second point to each other along a predetermined first direction parallel to a surface of a substrate, the ground portion being formed by grounding a conductor portion of the substrate on one side in a second direction orthogonal to the first direction and parallel to the surface of the substrate; a power feeding portion provided in a first range including the first point among the first range, a second range, and a third range that are obtained by dividing the linear portion of the ground portion into three equal parts along the first direction; and an element portion configured to receive power from the power feeding portion and formed in a conductor portion of the substrate that is insulated from the ground portion in a state in which the element portion protrudes from the first range toward the other side in the second direction with respect to the linear portion. The element portion includes a first element portion protruding from the linear portion in the first range toward the other side in the second direction, and a second element portion extending along the first direction from the first element portion toward the second point, spaced apart from the linear portion toward the other side in the second direction, and having at least one linear side.
The foregoing and additional features and characteristics of this disclosure will become more apparent from the following detailed description considered with the reference to the accompanying drawings, wherein:
An antenna device according to this disclosure is configured to transmit and receive circularly polarized radio waves. Hereinafter, an antenna device 1 according to the present embodiment will be described.
The antenna device 1 is provided on a substrate 2.
As shown in
As shown in
The one side in the second direction B is one end portion side of both end portions of the substrate 2 in the longitudinal direction. That is, in an example in
Here, the substrate 2 is formed by laminating a conductor and a dielectric. The conductor portion of the substrate 2 corresponds to the conductor that is laminated with such a dielectric to form the substrate 2. The ground portion 10 is formed by patterning such a conductor portion of the substrate 2 so as to include the linear portion 13, and is grounded. The linear portion 13 virtually connects the first point 11 set at the position spaced apart from the outer edge portion 2A of the substrate 2 on the one side in the first direction A toward the center side of the substrate 2 along the first direction A, and the second point 12 set at the position spaced apart from the outer edge portion 2B of the substrate 2 on the other side in the first direction A toward the center side of the substrate 2 along the first direction A.
In the present embodiment, the ground portion 10 includes a protruding portion 17 protruding from a second point 12 side of the linear portion 13 toward the other side in the second direction B with a predetermined width. The second point 12 side of the linear portion 13 means a side that is closer to the second point 12 than is a central portion of the linear portion 13 between the first point 11 and the second point 12.
Here, as described above, the linear portion 13 is provided between the first point 11 and the second point 12. The linear portion 13 is divided into three equal parts along the first direction A, and the three equal parts are referred to as a first range D1, a second range D2, and a third range D3. In this case, two points are required between the first point 11 and the second point 12. Of the two points, when a point closer to the first point 11 is referred to as a first auxiliary point 14 and a point closer to the second point 12 is referred to as a second auxiliary point 15, a portion of the linear portion 13 between the first point 11 and the first auxiliary point 14 corresponds to the first range D1. A portion of the linear portion 13 between the first auxiliary point 14 and the second auxiliary point 15 corresponds to the second range D2, and a portion of the linear portion 13 between the second auxiliary point 15 and the second point 12 corresponds to the third range D3.
In the present embodiment, the protruding portion 17 having the predetermined width and protruding toward the other side in the second direction B is provided in the third range D3 that is a range between the second auxiliary point 15 and the second point 12. The predetermined width is a width set according to a frequency of the radio waves transmitted and received by the antenna device 1. The other side in the second direction B is an outer edge portion 2C side as viewed from the linear portion 13 along the first direction A. Therefore, the ground portion 10 includes the protruding portion 17 protruding from the third range D3, which is the range between the second auxiliary point 15 and the second point 12, toward the outer edge portion 2C side, with the width set according to the frequency of the radio waves transmitted and received by the antenna device 1, as viewed from the linear portion 13 along the first direction A. In the present embodiment, the protruding portion 17 is formed in a rectangular shape in which a side along the first direction A is a short side and a side along the second direction B is a long side. In the shape of the protruding portion 17, a corner portion on an outer edge portion 2B side and an outer edge portion 2D side coincides with the second point 12. Similar to the ground portion 10, such a protruding portion 17 is formed by patterning a conductor portion of the substrate 2, and is formed of a conductor having the same potential in terms of direct current as a portion of the ground portion 10 formed on the one side with respect to the linear portion 13 in the second direction B.
As shown in
In the present embodiment, a distance between the first point 11 and the second point 12 is 0.33λ, a length of the protruding portion 17 along the first direction A is 0.03λ, and a length of the protruding portion 17 along the second direction B is 0.11λ.
The power feeding portion 20 is provided in the first range D1 including the first point 11 among the first range D1, the second range D2, and the third range D3 that are obtained by dividing the linear portion 13 of the ground portion 10 into three equal parts along the first direction A. The first range D1 is between the first point 11 and the first auxiliary point 14 in the linear portion 13. The power feeding portion 20 is provided in the first range D1. The power feeding portion 20 feeds power to the ground portion 10 described above and the element portion 30 to be described later such that the antenna device 1 transmits and receives radio waves propagating in the air. Specifically, the power feeding portion 20 applies a reference potential (0 V) from a power feeding point 21N to (grounds) the ground portion 10, and applies AC power of a predetermined frequency from a power feeding point 21L to the element portion 30. Therefore, the power feeding portion 20 is provided in the first range D1 of the linear portion 13 between the first point 11 and the first auxiliary point 14, applies the reference potential (0 V) to (grounds) the ground portion 10, and applies AC power of the predetermined frequency to the element portion 30. In the present embodiment, the power feeding point 21N and the power feeding point 21L are provided at positions that are 0.06λ away from the first point 11.
The element portion 30 receives power from the power feeding portion 20 and is formed in a conductor portion of the substrate 2 that is insulated from the ground portion 10 in a state in which the element portion 30 protrudes from the first range D1 toward the other side with respect to the linear portion 13 in the second direction B. “Receiving power from the power feeding portion 20” means receiving power fed from the power feeding portion 20 as described above. The first range D1 is a range from the first point 11 to the first auxiliary point 14 in the linear portion 13. The state in which the element portion 30 protrudes toward the other side with respect to the linear portion 13 in the second direction B means a state in which the element portion 30 protrudes from the linear portion 13 toward a side opposite to the ground portion 10 provided on the outer edge portion 2D side of the substrate 2 with respect to the linear portion 13, that is, toward the outer edge portion 2C side of the substrate 2 with respect to the linear portion 13, on the one side with respect to the linear portion 13 in the second direction B. The conductor portion of the substrate 2 that is insulated from the ground portion 10 refers to a conductor portion formed by patterning in a manner of being spaced apart, with a predetermined insulation distance, from the ground portion 10 formed by patterning the conductor portion of the substrate 2. Therefore, the element portion 30 receives power from the power feeding portion 20 at the power feeding point 21L and is formed in the conductor portion formed by patterning in a manner of being spaced apart, with the predetermined insulation distance, from the ground portion 10 formed by patterning the conductor portion of the substrate 2, in a state in which the element portion 30 protrudes from the linear portion 13 in a range of the linear portion 13 from the first point 11 to the first auxiliary point 14, toward the outer edge portion 2C side of the substrate 2 with respect to the linear portion 13.
In the present embodiment, the power feeding point 21L at which power is fed from the power feeding portion 20 to the element portion 30 is provided on the linear portion 13, and the element portion 30 includes a portion protruding toward the one side in the second direction B from the power feeding point 21L. Therefore, the ground portion 10 is formed by cutting in a manner of surrounding the portion of the element portion 30 including the power feeding point 21L. That is, the ground portion 10 includes a cutout portion 16 in the first range D1. In the element portion 30, the power feeding point 21L at which power is fed from the power feeding portion 20 may be provided on the other side with respect to the linear portion 13 in the second direction B, or may be provided on the one side with respect to the linear portion 13 in the second direction B.
The element portion 30 includes a first element portion 31 and a second element portion 32. The first element portion 31 protrudes from the first range D1 toward the other side in the second direction B. The first range D1 is the range between the first point 11 and the first auxiliary point 14 in the linear portion 13, and the first range D1 is provided with the power feeding point 21L of the element portion 30, at which power is fed from the power feeding portion 20. The other side in the second direction B is the outer edge portion 2C side of the substrate 2 as viewed from the linear portion 13. Therefore, the first element portion 31 includes the power feeding point 21L at which power is fed from the power feeding portion 20, and protrudes from the first range D1, which is the range between the first point 11 and the first auxiliary point 14 in the linear portion 13, toward the outer edge portion 2C side of the substrate 2 as viewed from the linear portion 13. In the present embodiment, as shown in
The second element portion 32 extends along the first direction A from the first element portion 31 toward the second point 12. As described above, the first element portion 31 protrudes from the first range D1 toward the outer edge portion 2C side of the substrate 2 as viewed from the linear portion 13. “Along the first direction A” means “so as to have a portion parallel to the linear portion 13”. “Toward the second point 12” means “toward the outer edge portion 2B side of the substrate 2 as viewed from the first element portion 31”. Therefore, the second element portion 32 extends from the first element portion 31, which protrudes from the first range D1 toward the outer edge portion 2C side of the substrate 2 when viewed from the linear portion 13, toward the outer edge portion 2B side of the substrate 2 when viewed from the first element portion 31 so as to have the portion parallel to the linear portion 13. Therefore, the second element portion 32 extends, along the second direction B, from a portion 41 of the rectangular first element portion 31 on the outer edge portion 2B side.
In the present embodiment, the ground portion 10 includes the protruding portion 17. As shown in
The first element portion 31 and the second element portion 32 described above are formed by patterning one conductor portion. Therefore, the first element portion 31 and the second element portion 32 are formed of conductors having the same potential in terms of direct current.
In the present embodiment, the second element portion 32 is gradually spaced apart from the linear portion 13 as the second element portion 32 approaches the second point 12 from the first element portion 31. “As the second element portion 32 approaches the second point 12 from the first element portion 31” means “as the second element portion 32 approaches the protruding portion 17 from the first element portion 31” in the present embodiment. “Gradually spaced apart from the linear portion 13” means that an outer edge portion 33 of the second element portion 32 on a linear portion 13 side is formed such that a distance between the outer edge portion 33 and the linear portion 13 gradually increases from a boundary portion 34 with the first element portion 31 along the first direction A to a closest portion 35 of the second element portion 32 closest to the protruding portion 17. Therefore, the outer edge portion 33 of the second element portion 32 on the linear portion 13 side is formed such that the distance between the outer edge portion 33 and the linear portion 13 gradually increases as the second element portion 32 approaches the protruding portion 17 from the first element portion 31.
In the present embodiment, the second element portion 32 is formed in a right-angled triangular shape, and a right-angled corner portion of the second element portion 32 coincides with a corner portion of the rectangular first element portion 31 on the outer edge portion 2B side and the outer edge portion 2C side. One of two sides of the right-angled triangle sandwiching the corner portion coincides with a side (portion 41) of the first element portion 31 on the outer edge portion 2B side, and the other of the two sides of the right-angled triangle sandwiching the corner portion is parallel to the linear portion 13. Therefore, an oblique side (corresponding to the outer edge portion 33) of the right-angled triangle faces the linear portion 13 side. Accordingly, as described above, the second element portion 32 can be formed such that the distance between the outer edge portion 33 and the linear portion 13 gradually increases as the second element portion 32 approaches the protruding portion 17 from the first element portion 31.
In other words, the second element portion 32 includes a reduced width portion 18 in which a width along an orthogonal direction orthogonal to an extending direction of the second element portion 32 extending from the first element portion 31 gradually decreases as the second element portion 32 approaches the second point 12 from the first element portion 31. The extending direction extending from the first element portion 31 is the first direction A. Therefore, the orthogonal direction orthogonal to the extending direction extending from the first element portion 31 corresponds to the second direction B orthogonal to the first direction A. Therefore, the second element portion 32 is formed such that the width along the second direction B gradually decreases as the second element portion 32 approaches the second point 12 from the first element portion 31. Such a portion may also be referred to as the reduced width portion 18.
In the present embodiment, a length of the element portion 30 along the first direction A is 0.17λ, and a length of the element portion 30 along the second direction B is 0·1λ. A distance X between an end portion of the reduced width portion 18 closest to the protruding portion 17 (closest portion 35) and the linear portion 13 may be equal to or greater than 0.04λ (preferably equal to or greater than 0.06λ).
As described above, the power feeding portion 20 grounds the ground portion 10 and feeds AC power to the element portion 30.
By continuously feeding such AC power, an electric field rotating about an axis along a direction orthogonal to both the first direction A and the second direction B as a rotation axis can be generated from the substrate 2. Therefore, by erecting the substrate 2, it is possible to transmit and receive circularly polarized radio waves as shown in
In the above embodiment, the element portion 30 includes the first element portion 31 having the rectangular shape in a plan view and the second element portion 32 having the right-angled triangular shape in the plan view. For example, as shown in
As shown in
The second element portion 32 may have a quadrangular shape in a plan view. In this case, as shown in
As shown in
In the above embodiments, the protruding portion 17 is described as being provided such that a corner portion on the outer edge portion 2B side and the outer edge portion 2D side coincides with the second point 12, but the protruding portion 17 may be provided such that the corner portion on the outer edge portion 2B side and the outer edge portion 2D side of the substrate 2 does not coincide with the second point 12. In this case, as shown in
In the above embodiments, a length of the ground portion 10 along the second direction B is greater than a length of the ground portion 10 along the first direction A, but a length of the ground portion 10 along the second direction B may be equal to or smaller than half of a length of the ground portion 10 along the first direction A as shown in
In the above embodiments, each size of the antenna device 1 is described using the wavelength A corresponding to the highest frequency in the frequency band used in the antenna device 1, which is only an example, and other values may be set.
In the above embodiments, the length of the protruding portion 17 along the first direction A is 0.03λ, and the length of the protruding portion 17 along the second direction B is 0.11λ. For example, a length of the protruding portion 17 along the first direction A may be 0.03λ and a length of the protruding portion 17 along the second direction B may be 0.23λ, or a length of the protruding portion 17 along the first direction A may be 0.085λ and a length of the protruding portion 17 along the second direction B may be 0.23λ. In this case, a distance between the protruding portion 17 and the element portion 30 may be 0.2λ or smaller (preferably 0.02λ to 0.07λ).
This disclosure can be applied to an antenna device.
A characteristic configuration of an antenna device according to this disclosure is an antenna device including: a ground portion including a linear portion connecting a first point and a second point to each other along a predetermined first direction parallel to a surface of a substrate, the ground portion being formed by grounding a conductor portion of the substrate on one side in a second direction orthogonal to the first direction and parallel to the surface of the substrate; a power feeding portion provided in a first range including the first point among the first range, a second range, and a third range that are obtained by dividing the linear portion of the ground portion into three equal parts along the first direction; and an element portion configured to receive power from the power feeding portion and formed in a conductor portion of the substrate that is insulated from the ground portion in a state in which the element portion protrudes from the first range toward the other side in the second direction with respect to the linear portion. The element portion includes a first element portion protruding from the linear portion in the first range toward the other side in the second direction, and a second element portion extending along the first direction from the first element portion toward the second point, spaced apart from the linear portion toward the other side in the second direction, and having at least one linear side.
According to such a characteristic configuration, it is possible to generate a difference between charge distribution in the ground portion including a conductor portion of the substrate and charge distribution in the element portion including another conductor portion of the substrate, the ground portion including the linear portion and being provided on the one side in the second direction, according to a phase of the power fed by the power feeding portion, and to generate an electric field rotating about an axis along a direction orthogonal to both the first direction and the second direction parallel to the surface of the substrate as a rotation axis based on the difference in the charge distribution. Therefore, it is possible to implement a small antenna device that can be used for transmission and reception of circularly polarized radio waves.
It is preferable that the ground portion includes a protruding portion protruding from a second point side of the linear portion toward the other side in the second direction with a predetermined width, and the second element portion extends from the first element portion toward the protruding portion.
According to this configuration, when there is a difference between the charge distribution in the ground portion including the linear portion and provided on the one side in the second direction, and the charge distribution in the element portion, according to the phase of the power fed by the power feeding portion, it is possible to generate the electric field between the ground portion including the linear portion and provided on the one side in the second direction, and the element portion. When there is a difference between charge distribution in the protruding portion and charge distribution in the element portion according to a phase of the power fed by the power feeding portion, it is possible to generate an electric field between the protruding portion and the element portion. Therefore, the circularly polarized radio waves can be more easily transmitted and received with the direction orthogonal to both the first direction and the second direction as an axis.
It is preferable that a length of the ground portion along the second direction is greater than a length of the ground portion along the first direction.
According to such a configuration, it is possible to easily generate a difference between charge distribution in the ground portion including the linear portion and provided on the one side in the second direction, and charge distribution in the protruding portion, according to a phase of the power fed by the power feeding portion. Therefore, it is possible to generate an electric field between the ground portion and the element portion and between the protruding portion and the element portion, the ground portion including the linear portion and being provided on the one side in the second direction, according to the phase of the power fed by the power feeding portion, and the circularly polarized radio waves can be more easily transmitted and received with the direction orthogonal to both the first direction and the second direction as the axis.
Alternatively, a length of the ground portion along the second direction may be equal to or smaller than half of a length of the ground portion along the first direction.
Even in such a configuration, it is possible to generate the difference between the charge distribution in the ground portion including the linear portion and provided on the one side in the second direction, and the charge distribution in the element portion, based on the power fed by the power feeding portion, and to generate the electric field between the ground portion including the linear portion and provided on the one side in the second direction, and the element portion. Therefore, the size of the antenna device capable of transmitting and receiving the circularly polarized radio waves can be further reduced.
It is preferable that the second element portion is formed to be gradually spaced apart from the linear portion as the second element portion approaches the second point from the first element portion.
With such a configuration, it is possible to reduce influence of the charge distribution in the ground portion including the linear portion and provided on the one side in the second direction on the charge distribution in the element portion. Therefore, it is possible to easily generate the electric field between the ground portion including the linear portion and provided on the one side in the second direction, and the element portion.
It is preferable that the second element portion includes a reduced width portion in which a width along an orthogonal direction orthogonal to an extending direction of the second element portion extending from the first element portion gradually decreases as the second element portion approaches the second point from the first element portion.
With such a configuration, it is possible to more easily reduce the influence of the charge distribution in the ground portion including the linear portion and provided on the one side in the second direction on the charge distribution in the element portion. It is possible to vary, in the element portion, an antenna length formed between a power feeding point at which the power is fed by the power feeding portion and a distal end portion of the second element portion closest to the second point. Therefore, it is possible to widen a band of radio waves that can be transmitted and received.
It is preferable that the second element portion further includes a constant width portion electrically connected to the reduced width portion on the second point side of the reduced width portion and having a constant width.
Even with such a configuration, it is possible to vary, in the element portion, the antenna length formed between the power feeding point at which the power is fed by the power feeding portion and the distal end portion of the second element portion closest to the second point.
It is preferable that the first element portion has a rectangular shape in a plan view, and the second element portion has a triangular shape in the plan view.
With such a configuration, the element portion can be easily processed.
The principles, preferred embodiment and mode of operation of the present invention have been described in the foregoing specification. However, the invention which is intended to be protected is not to be construed as limited to the particular embodiments disclosed. Further, the embodiments described herein are to be regarded as illustrative rather than restrictive. Variations and changes may be made by others, and equivalents employed, without departing from the spirit of the present invention. Accordingly, it is expressly intended that all such variations, changes and equivalents which fall within the spirit and scope of the present invention as defined in the claims, be embraced thereby.
Number | Date | Country | Kind |
---|---|---|---|
2021-183246 | Nov 2021 | JP | national |
Number | Name | Date | Kind |
---|---|---|---|
8174457 | Lam | May 2012 | B1 |
20080079635 | Rowell | Apr 2008 | A1 |
20160049732 | Huang | Feb 2016 | A1 |
20190044224 | Kim | Feb 2019 | A1 |
20210280970 | Ueda | Sep 2021 | A1 |
Number | Date | Country |
---|---|---|
2009-225068 | Oct 2009 | JP |
2016-116016 | Jun 2016 | JP |
WO 2017138800 | Aug 2017 | WO |
Number | Date | Country | |
---|---|---|---|
20230145638 A1 | May 2023 | US |