Patent Grant
11973279
The present disclosure relates to an antenna device and a communication apparatus.
A dielectric-loaded array antenna including plural unit antennas is known in which a dielectric equivalent is disposed on each of the unit antennas (see Patent Document 1). Patch antennas are used as the unit antennas, and a dielectric having the shape of a rectangular parallelepiped is disposed on each of the patch antennas. The length, the width, and the height of the dielectric are respectively 1.25 times, 1.25 times, and 1.42 times as large as the wavelength. By disposing the dielectric in this manner, the aperture efficiency of each unit antenna is enhanced.
As recognized by the present inventor, in a known patch antenna, the antenna gain in the direction directly in front of the patch antenna is maximized. Depending on the purpose of the antenna, however, it may be desirable to increase the antenna gain in a direction leaning (or tilted) from the direction directly in front of the antenna. In light of the feature, the present disclosure describes an antenna device and a communication apparatus that are able to increase the antenna gain in a direction leaning from the direction directly in front of the antenna device.
According to an aspect of the present disclosure, there is provided an antenna device including a substrate, a patch antenna, and a dielectric member. The patch antenna includes a radiation element disposed on the substrate, and a ground conductor disposed in or on the substrate. The dielectric member is disposed to at least partially cover, in a plan view, the radiation element, and is disposed on a side opposite a side on which the ground conductor is disposed as viewed from the radiation element. A body of resin material covers one or more sides of the dielectric member that are not in contact with the ground conductor or substrate. Under a condition a direction of a normal line to the radiation element is assumed as a height direction, a line which links centroids of horizontal sectional surfaces of the dielectric member in the height direction leans with respect to the direction of the normal line to the radiation element.
According to another aspect of the present disclosure, there is provided a communication apparatus including a housing and an antenna device contained in the housing. The antenna device includes a substrate and a patch antenna. The patch antenna includes a radiation element and a ground conductor, the radiation element being disposed in or on the substrate, the ground conductor being disposed in or on the substrate. The housing has a boundary surface, a permittivity of one side of the boundary surface being different from a permittivity of another side of the boundary surface, a high permittivity region on the one side of the boundary surface and a low permittivity region on the another side of the boundary surface being separated from each other by the boundary surface in an in-plane direction of the radiation element. The high permittivity region has another surface that does not oppose the low permittivity region and is at least partially covered by a body of resin material. The boundary surface tilts with respect to a top surface of the radiation element, and at least part of the boundary surface overlaps at least part of the radiation element from a plan view.
By disposing the above-described dielectric member, it is possible to increase the antenna gain in a direction leaning from the direction directly in front of a radiation element.
An antenna device according to a first embodiment will be described below with reference to
A dielectric member 20 is disposed on the substrate 10 (on the side of the substrate 10 opposite the side on which the ground conductor 15 is disposed as viewed from the radiation element 11) so that it covers the radiation element 11 as viewed from above. While the term “dielectric member” is used as a term of convenience, the dielectric member 20 is a body of material have a dielectric property. The dielectric member 20 is bonded to the radiation element 11 and the substrate 10 with an adhesive, for example. A feed line 12 is provided on the bottom surface of the substrate 10. The feed line 12 is coupled with the radiation element 11 by means of a via-hole within a clearance hole formed in the ground conductor 15 and extends on the positive side of the x axis.
The dielectric member 20 has a bottom surface facing the substrate 10 and a top surface opposing the bottom surface. The bottom surface is a square, each side of which has a length W, parallel with the x-axis direction and the y-axis direction. The center of the bottom surface of the dielectric member 20 and that of the radiation element 11 coincide with each other. The bottom surface of the dielectric member 20 contains the radiation element 11 as viewed from above. The top surface of the dielectric member 20 is located at a position at which the x component and the z component of the bottom surface are moved by translation in positive x and z vector directions. The dielectric member 20 also has four side surfaces which connect the top surface and the bottom surface. That is, the dielectric member 20 is a parallelepiped. A line linking the centroids of horizontal sectional surfaces of the dielectric member 20 tilts toward the positive direction of the x axis from the z-axis direction. Among the four side surfaces of the dielectric member 20, two side surfaces are perpendicular to the y-axis direction, while the remaining two side surfaces tilt with respect to the xy face. Outward-pointing normal vectors of the two remaining two surfaces are perpendicular to the y-axis direction.
The dielectric member 20 may be made of ceramics, such as low-temperature co-fired ceramics (LTCC), or a resin, such as polyimide. The relative permittivity εr of LTCC is about 6.4, while that of polyimide is about 3.
The height of the dielectric member 20 is represented by H. An x component of a length from the center of the bottom surface to that of the top surface of the dielectric member 20 is designated by dx (hereinafter called the amount of horizontal displacement). The angle (tilt angle) between the oblique surface and the positive direction of the z axis is represented by Oi. The length of each side of the radiation element 11 is represented by L, while the thickness of the radiation element 11 is indicated by T1. The thickness of the ground conductor 15 is designated by T2. Regarding the substrate 10, T3 designates the thickness between the radiation element 11 and the ground conductor 15, while T4 indicates the thickness of the substrate 10 under the ground conductor 15.
Advantages of the first embodiment will be described below.
In the first embodiment, the dielectric member 20 disposed on the radiation element 11 tilts with respect to the substrate 10. Radio waves radiated from the radiation element 11 are more likely to propagate through a space having a relatively high permittivity. The permittivity of the dielectric member 20 is higher than that of the atmospheric air, and so radio waves radiated from the radiation element 11 thus tend to propagate toward the tilting direction of the dielectric member 20. As a result, the antenna gain in a direction leaning from the direction directly in front of the radiation element 11 can be made higher than that in this front direction of the radiation element 11.
To verify the above-described advantages, a simulation was conducted. In the simulation, the length of each side of the radiation element 11 was 0.8 mm. Three antenna devices including dielectric members 20 whose bottom surfaces had different lengths W and different heights H and whose horizontal displacement dx have different amounts were prepared. Regarding the three antenna devices, the relationship between the antenna gain and the tilt angle θx toward the x-axis positive direction from the direction of a normal line was determined.
It is seen from the graph that the antenna gain is maximized in the direction of the dielectric member 20 directly in front of the radiation element 11. In contrast, the maximum gain for each of the two antennas having non-zero tilt angles θx occur at positive tilt angles. Moreover, the highest value of the antenna gain of each antenna device in the tilting direction of the dielectric member 20 is higher than that of the antenna device including a rectangular-parallelepiped dielectric member 20 in the same tilting direction. The tilt angle θx at which the antenna gain is maximized is substantially equal to the tilt angle θi of the oblique side surface of the dielectric member 20.
It is therefore validated from the simulation results shown in
Modified examples of the first embodiment will be described below. Although the bottom surface of the dielectric member 20 is a square in the first embodiment, it may have another quadrilateral shape, such as a rectangle having sides parallel with the x-axis direction and the y-axis direction. The bottom surface of the dielectric member 20 may have a shape of another polygon, a circle, or an ellipse, for example.
An antenna device according to a second embodiment will be described below with reference to
The shape of the bottom surface of the dielectric member 20 is a rectangle and the short sides of the rectangle have a length W. The shape of the top surface of the dielectric member 20 is a square and each side of the square has a length W.
Advantages of the second embodiment will be described below.
In the second embodiment, the side surface of the dielectric member 20 facing in the positive direction of the x axis is perpendicular to the bottom surface, while the side surface facing in the negative direction of the x axis tilts with respect to the xy face as in the first embodiment. With this configuration, as viewed from the radiation element 11 in the upward direction (the positive direction of the z axis), the dielectric member 20 tilts toward the positive side of the x axis. It is thus possible to increase the antenna gain in a direction leaning from the direction directly in front of the radiation element 11, as in the first embodiment.
In the first embodiment, the dielectric member 20 has a portion protruding as in the shape of the eaves (the right end portion on the top surface in
To verify the advantages of the second embodiment, a simulation similar to that in the first embodiment was conducted.
In the second embodiment, too, it is verified that the antenna gain is maximized in a direction leaning from the direction directly in front of the radiation element 11. As the tilt angle θi of the side surface becomes greater, the tilt angle θx at which the antenna gain is maximized also becomes greater.
An antenna device according to a third embodiment will now be described below with reference to
In the third embodiment, too, when the direction of a normal line to the radiation element 11 (z-axis direction) is assumed as the height direction, a line linking the centroids of horizontal sectional surfaces of the dielectric member 20 in the height direction leans with respect to the direction of the normal line to the radiation element 11. With this configuration, as in the first and second embodiments, the antenna gain is maximized in a direction leaning from the direction directly in front of the radiation element 11. As a result of changing the orientation of tilt 22, the direction in which the antenna gain is maximized can be adjusted as desired.
In this modified example, too, when the direction of a normal line to the radiation element 11 (z-axis direction) is assumed as the height direction, a line linking the centroids of horizontal sectional surfaces of the dielectric member 20 in the height direction leans with respect to the direction of the normal line to the radiation element 11. With this configuration, as in the third embodiment, the antenna gain is maximized in a direction leaning from the direction directly in front of the radiation element 11. As a result of changing the orientation of tilt 22, the direction in which the antenna gain is maximized can be adjusted as desired.
An antenna device according to a fourth embodiment will now be described below with reference to
The dielectric member 20 associated with the radiation element 11BB at the center has a truncated conical shape. The dielectric members 20 associated with the eight surrounding radiation elements 11 tilt in the directions of imaginary lines radially extending from the centroid of the array antenna (the center of the central radiation element 11). This will be explained more specifically. The dielectric members 20 for the two radiation elements 11BC and 11BA respectively located on the positive side and the negative side of the x axis with respect to the central radiation element 11BB respectively tilt in the positive direction and the negative direction of the x axis. The dielectric members 20 for the two radiation elements 11AB and 11CB respectively located on the positive side and the negative side of the y axis with respect to the central radiation element 11 respectively tilt in the positive direction and the negative direction of the y axis. The shapes of the dielectric members 20 associated with the radiation elements 11AB, 11BA, 11BC, and 11CB are the same as that of the dielectric member 20 of the first embodiment (
The dielectric member 20 for the radiation element AC positioned at an angle of 45° in the positive direction of the x axis and in the positive direction of the y axis with respect to the central radiation element 11 tilts at an angle of 45° in the positive direction of the x axis and in the positive direction of the y axis. Among the nine radiation elements 11 disposed in a matrix of three rows and three columns, the dielectric members 20 associated with the three radiation elements 11AA, 11CA, 11CC located at the other corners tilt in a manner similar to the dielectric member 20 associated with the radiation element AC. The shapes of the dielectric members 20 for the radiation elements 11AA, 11AC, 11CA, and 11CC are the same as that of the dielectric member 20 of the third embodiment (
Regarding each of the dielectric members 20 other than the dielectric member 20 associated with the central radiation element 11, a line linking the centroids of horizontal sectional surfaces of such a dielectric member 20 in the height direction tilts outward (away from a direction normal to a main surface of the substrate) as viewed from the centroid of the array antenna.
Advantages of the fourth embodiment will be described below. In the fourth embodiment, when focusing on each element unit 25, it is seen that the direction in which the antenna gain is maximized leans to radiate outwardly with respect to the direction directly in front of the radiation element 11. A high antenna gain can thus be obtained in a wider range of directions leaning from the directions directly in front of the respective radiation elements 11.
A simulation was conducted to verify the above-described advantages and will be discussed below. In the simulation, the length of each side of the radiation element 11 was 0.8 mm. The center-to-center distance between the radiation elements 11 in the x-axis direction and in the y-axis direction was 2.5 mm. Regarding the dielectric member 20 associated with the central radiation element 11BB, the diameter of the bottom surface was 2 mm, the diameter of the top surface was 0.6 mm, and the height was 1 mm. The dimension of the bottom surface of each of the eight surrounding dielectric members 20 in the x-axis direction was 1.6 mm, while that in the y-axis direction was 1.5 mm. The amount of horizontal displacement of the dielectric members 20 associated with the radiation elements 11AB, 11BA, 11BC, and 11CB was 1 mm. The amount of horizontal displacement of the dielectric members 20 associated with the radiation elements 11AA, 11AC, 11CA, and 11CC in the x-axis direction and that in the y-axis direction were both 1 mm.
In the fourth embodiment, in comparison with the antenna device without any dielectric member 20, not only the antenna gain in the direction directly in front of the radiation element 11, but also the antenna gain in the directions leaning from the direction directly in front of the radiation element 11 is increased. It is thus validated from the simulation results that, as a result of disposing the dielectric members 20 as in the antenna device of the fourth embodiment, the antenna gain in the direction directly in front of the radiation element 11 and also in directions leaning from this front direction of the radiation element 11 can be increased.
In the ranges in which the absolute value of the tilt angle θx in the x-axis direction is larger than about 60° and that of the tilt angle θy in the y-axis direction is larger than about 30°, the gain of the antenna device of the fourth embodiment becomes higher than that of the antenna device including a dielectric member 20 formed in a rectangular parallelepiped. In this manner, the antenna gain can be increased in a range in which the side surface of the dielectric member 20 tilts with respect to the direction of a normal line by a larger angle.
Modified examples of the fourth embodiment will be discussed below.
In the fourth embodiment, the nine element units 25 (
An antenna device according to a fifth embodiment will be described below with reference to
In the fifth embodiment, too, when the direction of a normal line to the radiation element 11 is assumed as the height direction, a line linking the centroids of horizontal sectional surfaces of the dielectric member 20 in the height direction leans with respect to the direction of the normal line to the radiation element 11. With this configuration, as in the first and second embodiments, a high antenna gain can be obtained in a direction leaning from the direction directly in front of the radiation element 11.
An antenna device according to a sixth embodiment will be described below with reference to
Advantages of the sixth embodiment will be described below. Since the permittivity of the dielectric member 20 is higher than that of the surrounding sealing resin 30, radio waves radiated from the radiation element 11 propagate toward the tilting direction of the dielectric member 20. Hence, as in the first embodiment, the antenna gain in a direction leaning from the direction directly in front of the radiation element 11 can be made higher than that in this front direction of the radiation element 11. Additionally, because of the sealing resin 30 sealing the dielectric member 20, damage to the dielectric member 20 due to the falling off from the antenna device, for example, can be reduced.
A modified example of the sixth embodiment will be discussed below with reference to
In this modified example, a line linking the centroids of horizontal sectional surfaces of the dielectric member 20 in the height direction leans with respect to the direction of a normal line to the radiation element 11. With this configuration, as in the sixth embodiment, the antenna gain in a direction leaning from the direction directly in front of the radiation element 11 can be made higher than that in this front direction of the radiation element 11. The shape of the dielectric member 20 may not necessarily be part of a geometrically precise spheroid. The surface other than the bottom surface may be a desired curved face.
An antenna device according to a seventh embodiment will be described below with reference to
Advantages of the seventh embodiment will be discussed below. In the seventh embodiment, because of multi-resonance generated by the radiation element 11 and the parasitic element 21, the operating bandwidth of the antenna device is increased. Additionally, the parasitic element 21 is disposed at a position displaced from the radiation element 11 toward the tilting direction of the dielectric member 20. This enhances the effect of causing the antenna gain in a direction leaning from the direction directly in front of the radiation element 11 to be higher than that in this front direction of the radiation element 11.
Modified examples of the seventh embodiment will now be explained below with reference to
A communication apparatus according to an eighth embodiment will be described below with reference to
The housing 35 includes a high permittivity portion 35A having a relatively high permittivity and low permittivity portions 35B having a relatively low permittivity. The high permittivity portion 35A and the low permittivity portions 35B are separated from each other in the in-plane direction of the top surface of the radiation element 11. The high permittivity portion 35A is disposed at a position at which it covers the radiation element 11 as viewed from above. The antenna device is positioned and fixed in the housing 35 so that the high permittivity portion 35A is disposed over the radiation element 11 with a gap therebetween. The antenna device may be positioned in the housing 35 so that the high permittivity portion 35A contacts the radiation element 11. As discussed with other embodiments, a resin body may optionally be included on one or more exposed surfaces of the high permittivity portion 35A.
The high permittivity portion 35A is sandwiched between the two low permittivity portions 35B. Boundary surfaces 36 and 37 separating the high permittivity portion 35A and the low permittivity portions 35B from each other are parallel with each other and tilt with respect to the top surface of the radiation element 11. The boundary surface 36 overlaps an edge of the radiation element 11 as viewed from above. As viewed from above, the boundary surface 36 tilts so as to enter the inside of the radiation element 11 from the outside of the radiation element 11 as it separates from the radiation element 11 toward the direction of a normal line to the radiation element 11. The high permittivity portion 35A is positioned toward the radiation element 11 from the boundary surface 36. The other boundary surface 37 is positioned outside the radiation element 11 as viewed from above.
Advantages of the eighth embodiment will be discussed below.
In the eighth embodiment, the high permittivity portion 35A, which is part of the housing 35, functions similarly to the dielectric member 20 of the antenna device of the first embodiment. Hence, in the eighth embodiment, as well as in the first embodiment, the antenna gain in a direction leaning from the direction directly in front of the radiation element 11 can be made higher than that in this front direction of the radiation element 11.
In the eighth embodiment, an antenna device having typical directivity characteristics is used, and desired directivity characteristics of a communication apparatus can be implemented by adjusting the size and the shape of the high permittivity portion 35A of the housing 35 for storing the antenna device and also by adjusting the positional relationship between the high permittivity portion 35A and the radiation element 11.
Modified examples of the eighth embodiment will be explained below with reference to
In this modified example, a side surface 41, which is one of the two surfaces of the slit 38, tilting to separate from the substrate 10 functions as the boundary surface 36 of the antenna device of the eighth embodiment (
A communication apparatus according to a ninth embodiment will be described below with reference to
Part of the housing 35 opposes the top surface of the substrate 10 of the antenna device 40 with a spacing therebetween. The portion of the housing 35 opposing the top surface of the substrate 10 (hereinafter such a portion will be called an antenna opposing portion) is formed of a conductive material, such as a metal. Multiple apertures 45 are formed at the antenna opposing portions of the housing 35. The multiple apertures 45 are located in association with the respective element units 25 each constituted by a radiation element 11 and a dielectric member 20. As viewed from above, the apertures 45 each have a shape of an ellipse or a racetrack extending in the tilting direction of the dielectric member 20 from the region where the radiation element 11 is disposed. The aperture 45 associated with the central element unit 25 is circular.
Advantages of the ninth embodiment will be described below.
In the ninth embodiment, radio waves emitted from the radiation elements 11 are not blocked by the housing 35 made of a metal, for example, and are instead radiated to a space outside the housing 35 via the associated apertures 45. As viewed from above, the apertures 45 each have an elongated shape extending in the tilting direction of the dielectric member 20 from the region where the radiation element 11 is disposed. Radio waves emitted in a direction leaning from the direction of a normal line to the radiation element 11 can thus be radiated efficiently to the outside of the housing 35. It is preferable that the apertures 45 be each formed in size and shape which covers a 3-dB beamwidth of the associated radiation element 11.
Modified examples of the ninth embodiment will be explained below.
Although the apertures 45 have a shape of an ellipse or a racetrack in the ninth embodiment, they may have a different shape. In the ninth embodiment, the apertures 45 are open, but they may be closed with the dielectric member.
The above-described embodiments are only examples. The configurations described in different embodiments may partially be replaced by or combined with each other. Similar advantages obtained by similar configurations in plural embodiments are not repeated in the individual embodiments. The present disclosure is not restricted to the above-described embodiments. It is to be understood that variations, improvements, and combinations, for example, will be apparent to those skilled in the art.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2018-181164 | Sep 2018 | JP | national |
The present application is a continuation of and claims priority to PCT/JP2019/033977, filed Aug. 29, 2019, which claims priority to JP 2018-181164, filed Sep. 27, 2018, the entire contents of each are incorporated herein by its reference.
| Number | Name | Date | Kind |
|---|---|---|---|
| 20040119646 | Ohno | Jun 2004 | A1 |
| 20080142916 | Baldi | Jun 2008 | A1 |
| 20150346334 | Nagaishi et al. | Dec 2015 | A1 |
| 20190027804 | Kim | Jan 2019 | A1 |
| Number | Date | Country |
|---|---|---|
| 0 280 379 | Aug 1988 | EP |
| 63-224507 | Sep 1988 | JP |
| 1-243605 | Sep 1989 | JP |
| 3-10407 | Jan 1991 | JP |
| 5-48319 | Feb 1993 | JP |
| 7-249931 | Sep 1995 | JP |
| 2015-213285 | Nov 2015 | JP |
| 2015-226297 | Dec 2015 | JP |
| 2014125716 | Aug 2014 | WO |
| Entry |
|---|
| Japanese Office Action dated Sep. 14, 2021, in corresponding Japanese Patent Application No. 2020-548244. |
| International Search Report and Written Opinion dated Oct. 1, 2019, received for PCT Application PCT/JP2019/033977, Filed on Aug. 29, 2019, 9 pages including English Translation. |
| Chinese Office Action dated May 17, 2023, in corresponding Chinese Patent Application No. 201980063763.1, 11pp. |
| Written Opinion of the International Searching Authority dated Oct. 1, 2019, received for PCT Application PCT/JP2019/033977, Filed on Aug. 29, 2019, 6 pages. (Previously filed; submitting English translation only.). |
| Number | Date | Country | |
|---|---|---|---|
| 20210234278 A1 | Jul 2021 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2019/033977 | Aug 2019 | US |
| Child | 17213259 | US |
