Patent Application
20240405412
The present disclosure relates to a vehicle antenna device and an antenna module.
Heretofore, a structure has been known that a casing which stores a substrate on which a plurality of antennas for communication with outside, such as a GNSS (Global Navigation Satellite System) antenna, a V2X (Vehicle to Everything) antenna and a LTE (Long Term Evolution) antenna are mounted, is attached to the inner surface of a vehicle windshield (e.g. Patent Document 1).
However, if a satellite antenna such as a GNSS antenna and a communication antenna such as a V2X antenna are mounted on one common substrate, it tends to be difficult to secure isolation between the two antennas and it may sometimes be difficult to secure desired antenna characteristics of the respective antennas, such as antenna gain and directivity. For example, radio waves which the communication antenna transmits/receives to/from outside the vehicle in a horizontal direction, may interfere with radio waves which arrive from a satellite in a zenith direction, thus impairing the antenna characteristics of the satellite antenna and the communication antenna.
The present disclosure provides a vehicle antenna device which can secure desired antenna characteristics of both a satellite antenna and a communication antenna, and an antenna module.
According to an aspect of the present disclosure, provided is a vehicle antenna device comprising
According to another aspect of the present disclosure, provided is an antenna module which can be installed in the vicinity of a conductor plate placed adjacent to a dielectric plate attached to a vehicle, which comprises, in a state where the antenna module is installed in the vicinity of the conductor plate,
According to the present disclosure, provided are a vehicle antenna device which can secure desired antenna characteristics of both a satellite antenna and a communication antenna, and an antenna module.
Embodiments of the present disclosure will now be described below with reference to the drawings. For easy understanding, the scales of the individual members in the drawings may be represented differently from those of the actual members. Terms representing directions, such as “parallel”, “at right angles”, “orthogonal”, “horizontal”, “perpendicular”, “top-bottom”, and “left-right”, are not necessarily to be interpreted in an exact sense, and a certain range of deviation is allowed as long as the operations and the effects of the embodiment are not impaired. The shape of a corner is not limited to a right angle, and the corner may be rounded and arched. The X axis direction, the Y axis direction and the Z axis direction respectively represent a direction parallel to the X axis, a direction parallel to the Y axis and a direction parallel to the Z axis. The X axis direction, the Y axis direction and the Z axis direction are orthogonal to one another. The wording “face” is not limited to a meaning that an object entirely faces another object but may include a meaning that the object partly faces another object, and the wording “overlap” is not limited to a meaning that an object entirely overlap another object but may include a meaning that the object partly overlap another object.
Examples of the window glass of a vehicle in the present embodiment include a windshield attached to the front side of a vehicle, a rear glass attached to the rear side of a vehicle, a side glass attached to the lateral sides of a vehicle, and a roof glass attached to the ceiling of a vehicle. The window glass of a vehicle is not limited to these examples. For example, it may be a window glass having a roof glass integrated with one or both of a windshield and a rear glass.
In
The dielectric plate 1 is a plate-shaped member containing a dielectric as the main component. The dielectric may be glass or a resin. Specific examples of the dielectric plate 1, other than a window glass, include a resin window, a resin plate and a resin door.
The dielectric plate 1 may be a transparent (including translucent) member which transmits visible light, or may be a member provided with a light shielding film (not shown) which partially blocks visible light. Specific examples of the light shielding film include a ceramic film such as a black ceramic film. When the antenna module 201 and a housing 302 described hereinafter are disposed so as to overlap the light shielding film from a vertical view from above outside the vehicle, the antenna module 201 and the housing 302 are hardly visible from outside the vehicle, and the design of the vehicle tends to improve.
The conductor plate 2 is a conductive plate-shaped member placed adjacent to the dielectric plate 1. A state where the conductor plate 2 is placed adjacent to the dielectric plate 1, is not limited to a state where it is a certain distance apart from the dielectric plate 1 but includes a state where it is in contact with the dielectric plate 1. The conductor plate 2 is positioned, in the example shown in
The conductor plate 2 may be a plate member exposed (to the vehicle interior side) or may be a plate member covered with a resin member.
The conductor plate 2 is not limited to a metal plate stored in the housing 302 and may be another conductive plate-shaped member. For example, the conductor plate 2 may be a plate-shaped portion of a vehicle body frame or a vehicle door, or may be a window frame of e.g. a flange to which a window glass is to be attached.
The antenna module 201 is a module having a plurality of antennas, and is installed in the vicinity of the dielectric plate 1 and the conductor plate 2. The antenna module 201 is disposed in a space on the vehicle interior side relative to the dielectric plate 1, and is fixed by a fixing member (not shown) so that its position relative to the dielectric plate 1 is fixed. The antenna module 201 has a satellite antenna 10 which receives radio waves arriving from a satellite through the dielectric plate 1 and a communication antenna 20 which transmits/receives radio waves to/from outside the vehicle through the dielectric plate 1 in a horizontal direction.
In the antenna device 101, the conductor plate 2, the satellite antenna 10 and the communication antenna 20 are disposed in this order from upper to lower portion of the vehicle. That is, the satellite antenna 10 is disposed below the conductor plate 2, and the communication antenna 20 is disposed below the satellite antenna 10.
The wording “the satellite antenna 10 is disposed below the conductor plate 2” means that the satellite antenna 10 is present in a space between the conductor plate 2 and the vehicle bottom. Thus, the state where the satellite antenna 10 is disposed below the conductor plate 2 is not limited to a state where the satellite antenna 10 does overlap the conductor plate 2 from a vertical view but includes a state where the satellite antenna 10 does not overlap the conductor plate 2 from a vertical view as shown in
Likewise, the wording “the communication antenna 20 is disposed below the satellite antenna 10” means that the communication antenna 20 is present in a space between the satellite antenna 10 and the vehicle bottom. Thus, the state where the communication antenna 20 is disposed below the satellite antenna 10 is not limited to a state where the communication antenna 20 does overlap the satellite antenna 10 from a vertical view as shown in
The satellite antenna 10 has, in this example, a radiating conductor 11 the normal direction of which faces upward and a ground conductor 15 the normal direction of which faces upward. The radiating conductor 11 and the ground conductor 15 are disposed in this order from upper to lower portion of the vehicle.
The radiating conductor 11 does not overlap the conductor plate 2 from a vertical view. Thus, radio waves arriving from a satellite in a zenith direction will hardly be blocked by the conductor plate 2, and the radiating conductor 11 can receive the radio waves with high gain with desired directivity.
The ground conductor 15 is positioned between the radiating conductor 11 and the communication antenna 20. The ground conductor 15 being positioned between the radiating conductor 11 and the communication antenna 20 means that the ground conductor 15 is present in a space between the radiating conductor 11 and the communication antenna 20. In other words, the ground conductor 15 is present in a position which crosses a line segment connecting an optional point on the radiating conductor 11 and an optional point on a radiating plate 21 of the communication antenna 20.
By the ground conductor 15 being positioned between the radiating conductor 11 and the communication antenna 20, the ground conductor 15 functions as a means to secure isolation between the satellite antenna 10 and the communication antenna 20. Therefore, interference between radio waves which the communication antenna 20 transmits/receives to/from outside the vehicle in a horizontal direction, and radio waves which arrive from a satellite in a zenith direction, is suppressed, and thus the antenna characteristics of the satellite antenna 10 and the communication antenna 20 can be secured.
The satellite antenna 10 is, for example, a patch antenna in which the dielectric layer is interposed between the radiating conductor and the ground conductor. In the example shown in
The radiating conductor 11 is a first radiating element which receives radio waves in a first frequency band arriving from a satellite, and the radiating conductor 13 is a second radiating element which receives radio waves in a second frequency band arriving from a satellite. The second frequency band is a frequency band different from the first frequency band. For example, in a case where the satellite antenna 10 is a GNSS antenna, the first frequency band is a 1.2 GHz band including a frequency of L5 waves, and the second frequency band is a 1.6 GHz band including a frequency of L1 waves.
The radiating conductor 11 and the radiating conductor 13 are radiating elements differing in the size, and in this example, the radiating conductor 13 is larger than the radiating conductor 11. The radiating conductor 11, 13 may, for example, be a planar rectangular conductor pattern which receives circularly polarized waves, but the shape of the radiating conductor 11, 13 is not limited thereto. For example, when the radiating conductor 11, 13 has an oblique truncation on two corners on a diagonal of the rectangular conductor, only one feeding point to be connected to the radiating conductor 11, 13 is necessary. The truncation corresponds to a known degeneracy removal element or perturbation element, and the area of the truncation removed from the rectangular conductor is set as an area determined by degeneracy removal method. The satellite antenna 10 may have such a configuration that it has only one of the radiating conductor 11 and the radiating conductor 13. For example, in a case where the satellite antenna 10 is a GNSS antenna, it may be an antenna which can receive only the above first frequency band (1.2 GHz band) or may be an antenna which can receive only the above second frequency band (1.6 GHz band). In such a case, the satellite antenna 10 may have only one of the dielectric layers 12 and 14, and have one radiating conductor, one dielectric layer and the ground conductor 15 laminated from above.
The dielectric layer 12 is a dielectric interposed between the radiating conductor 11 and the radiating conductor 13. The dielectric layer 12 is, for example, a dielectric substrate having a front surface on which the radiating conductor 11 is formed and a rear surface on which the radiating conductor 13 is formed. The radiating conductor 11 is formed substantially at the center portion on the front surface of the dielectric layer 12, and the radiating conductor 13 is formed on almost the entire rear surface of the dielectric layer 12. Specific examples of the dielectric layer 12 include a ceramic substrate.
The insulating layer 14 is an insulator interposed between the radiating conductor 13 and the ground conductor 15. The insulating layer 14 is, for example, a base formed e.g. by a resin.
The ground conductor 15 is a base board which is larger in area than the insulating layer 14. The ground conductor 15 has a larger area than the radiating conductor 13.
The radiating conductor 11 and the radiating conductor 13 are electrically connected to one end of a signal line of a feeding cable such as a coaxial cable, and the ground conductor 15 is electrically connected to a ground wire of the feeding cable. The other end of the signal line is connected to a receiving device which processes signals output from the satellite antenna 10.
The satellite antenna 10 is, for example, a GNSS antenna. The GNSS (Global Navigation Satellite System) generically means satellite positioning system such as GPS of the United States, Quasi-Zenith Satellite System (QZSS) of Japan, GLONASS of Russia, Galileo of Europe, BeiDou of China, and NAVIC of India. The satellite antenna 10 is not limited to a GNSS antenna, and may be an antenna to be used for Satellite Digital Audio Radio Service (SDARS) or low earth orbit satellite communication.
The communication antenna 20 is, for example, a patch antenna in which the dielectric layer is interposed between the radiating conductor and the ground conductor. In the example shown in
The radiating plate 21 is a radiating element which transmits/receives radio waves in a third frequency band to/from a communication device outside the vehicle. The third frequency band at which the radiating plate 21 of the communication antenna 20 conduct transmitting/receiving, may or may not overlap the first frequency band at which the radiating conductor 11 of the satellite antenna 10 conduct transmitting/receiving, or the second frequency band at which the radiating conductor 13 of the satellite antenna 10 conduct transmitting/receiving. The radiating plate 21 is, for example, a planar rectangular conductor pattern which transmits/receives vertically polarized waves or horizontally polarized waves, but the shape of the radiating plate 21 is not limited thereto.
The dielectric layer 22 is a dielectric interposed between the radiating plate 21 and the ground plate 23. The dielectric layer 22 is, for example, a dielectric substrate having a front surface on which the radiating plate 21 is formed and a rear surface on which the ground plate 23 is formed. The radiating plate 21 is formed substantially at the center portion on the front surface of the dielectric layer 22, and the ground plate 23 is formed on almost the entire rear surface of the dielectric layer 22. Specific examples of the dielectric layer 12 include a ceramic substrate.
The ground plate 23 is a conductor plate which is the same in area as the radiating plate 21 or larger in area than the radiating plate 21.
The radiating plate 21 is electrically connected to one end of a signal line of a feeding cable such as a coaxial cable, and the ground plate 23 is electrically connected to a ground wire of the feeding cable. The other end of the signal line is connected to a communication device which processes signals input/output from/to the communication antenna 20. Further, the communication antenna 20 may have one or more parasitic conductor plates (not shown) apart from the radiating plate 21 and the ground plate 23. For example, on a surface of the dielectric layer 22, shared with the radiating plate 21, two parasitic conductor plates in total in the vehicle width direction (+Y axis direction, −Y axis direction) apart from the radiating plate 21, may be provided. When the communication antenna 20 has the parasitic conductor plate, the antenna gain in the vehicle width direction in the horizontal plane improves, and directivity in a wide range is likely to be obtained.
The third frequency band at which the communication antenna 20 conduct transmitting/receiving is, for example, a radio frequency band of microwaves and millimeter waves (0.3 GHz to 300 GHz, for example), for example. Specific examples of the third frequency band include sub6 band (3.6 GHz to 6 GHz, for example), 2.4 GHz band, 5.2 GHz band, 5.3 GHZ band, 5.6 GHz band, 5.8 GHz band, and 5.9 GHZ band.
As the communication antenna 20, for example, a V2X (Vehicle to Everything) antenna, which is used for vehicle-to-vehicle communication and vehicle-to-road communication, is suitably used. The V2X antenna is capable of transmitting and receiving radio waves of a narrowband, such as a 5.8 GHz band and a 5.9 GHz band, for example, and is developed for various applications, such as the European ETC (Electronic Toll Collection) system. The communication antenna 20 is not limited to a V2X antenna and may be an antenna which can be used for other applications such as 5G, 6G, and vehicle radar system.
The communication antenna 20 may, as shown in
An end 15a on the conductor plate 2 side of the ground conductor 15 of the satellite antenna 10, and an end 23a on the conductor plate 2 side of the conductor of the communication antenna 20, may be on one vertical plane 5 corresponding to the YZ plane, whereby the communication antenna 20 and the satellite antenna 10 are positioned closer to the conductor plate 2, and thus the antenna device 101 can be made smaller in size. The end 23a may be an upper end of the ground plate 23 or a portion at the same potential as the ground plate 23. The portion at the same potential as the ground plate 23 is, for example, a ground terminal of a connector to which one end of a coaxial cable is to be connected. The end 23a on the conductor plate 2 side of the conductor of the communication antenna 20 may be positioned on the +X axis direction (the vehicle interior side) as compared with the disposition shown in
The communication antenna 20 is, for example, a patch antenna having the radiating plate 21 the normal direction of which extends at an angle within ±5° relative to the horizontal plane and the ground plate 23 which faces the conductor plate 2 side of the radiating plate 21. In this case, as compared with a form in which the normal direction of the radiating plate 21 extends (is inclined) at an angle exceeding ±5° relative to the horizontal direction, the angle at which radio waves transmitted from the communication antenna 20 in the horizontal direction are reflected on the ground conductor 15 of the satellite antenna 10 becomes smaller. As a result, the radio waves around the normal of the radiating plate 21 tend to be intense, and the communication antenna 20 can transmit/receive radio waves with high gain to/from outside the vehicle through the dielectric plate 1 in the horizontal direction. In a case where the communication antenna 20 is a V2X antenna, according to the communication standards, the normal direction (the angle of elevation or the angle of depression) of the radiating plate 21 may optionally be adjusted within a range of +5°.
The angle θ which is formed by a straight line 6 connecting the upper end 21a of the radiating plate 21 and an end 15b of the ground conductor 15 on the opposite side from the conductor plate 2, with a reference plane 7 which passes the upper end 21a of the radiating plate 21 and which is perpendicular to the radiating plate 21, may be 10° or greater. When the angle θ is 10° or greater, radio waves around the normal of the radiating plate 21 tend to be intense, and the communication antenna 20 can transmit/receive radio waves with high gain to/from outside the vehicle through the dielectric plate 1 in the horizontal direction. In order that the communication antenna 20 can transmit/receive radio waves with high gain in the horizontal direction, the angle θ is preferably 12° or greater, more preferably 15° or greater, further preferably 20° or greater.
The dielectric plate 1 may be inclined relative to the horizontal plane, or may be parallel to the horizontal plane. The dielectric plate 1 inclined relative to the horizontal plane is, for example, a window glass (more specifically a windshield) inclined at an angle α of greater than 0° and 50° or smaller relative to the horizontal plane. The angle α formed by the dielectric plate 1 and the horizontal plane may be 40° or smaller, and may be 30° or smaller. The angle α may be 10° or greater, may be 15° or greater, and may be 20° or greater. The dielectric plate 1 parallel to the horizontal plane (the dielectric plate 1 with an angle α substantially equal to 0) is, for example, a roof glass.
The satellite antenna 10 and the communication antenna 20 may be stored in one housing 3, or may be stored in separate housings. When they are stored in one housing 3, the antenna module 201 can be made small in size.
As shown in
As shown in
As shown in
The conductor plate 2, the satellite antenna 10 and the communication antenna 20 may not overlap one vertical plane 8. For example, two of the conductor plate 2, the satellite antenna 10 and the communication antenna 20 may overlap one vertical plane 8, and the other one does not overlap the one vertical plane 8. For example, the satellite antenna 10 may be positioned on the positive side of the Y axis direction relative to the vertical plane 8 so as not to overlap the vertical plane 8, and the communication antenna 20 may be positioned on the negative side of the Y axis direction relative to the vertical plane 8 so as not to overlap the vertical plane 8.
The upper hemisphere average gain of the satellite antenna 10 was measured at +3.2 dBi when L=−10 mm, and was measured at +3.0 dBi when L=0 mm. That is, in a case where the satellite antenna 10 deviated 10 mm from the conductor plate 2 into the negative side of the axis direction (vehicle front side) (L=−10 mm), as compared with a case where the satellite antenna 10 did not deviate (L=0 mm), radio wave shielding by the conductor plate 2 decreased, and the antenna characteristics of the satellite antenna 10 improved.
In the embodiment shown in
The average gain around the entire periphery of a plane inclined 10° relative to the horizontal plane which passes the center of gravity of the radiating plate 21, was measured at +2.0 dBi in
The average gain around the entire periphery of a plane inclined 10° relative to the horizontal plane which passes the center of gravity of the radiating plate 21, was measured at +2.2 dBi in
The present invention has been described with reference to the above-mentioned embodiments, however, the technique of the present disclosure is not limited to the above-mentioned embodiments. Various changes and modifications such as combination and replacement with other embodiments partly or entirely are possible.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-019909 | Feb 2022 | JP | national |
This application is a continuation of PCT Application No. PCT/JP2023/003811, filed on Feb. 6, 2023, which is based upon and claims the benefit of priority from Japanese Patent Application 2022-019909 filed on Feb. 10, 2022. The contents of those applications are incorporated herein by reference in their entireties.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2023/003811 | Feb 2023 | WO |
| Child | 18799844 | US |
