阅读说明：本技术 天线系统 (Antenna system ) 是由 佐山稔贵 奥田崚太 茂木健 加贺谷修 于 2019-10-01 设计创作，主要内容包括：一种天线系统,具备：玻璃板,厚度为1.1mm以上且介电损耗角正切为0.005以上；和天线,位于从所述玻璃板的一面分离的位置,将向所述天线输入的功率与从所述天线向空间中辐射的功率的比设为辐射效率,在将频率10GHz以上的规定频率的电波的波长设为λ,将使所述玻璃板与所述天线接触时的辐射效率设为η-0[dB],将使所述一面与所述天线之间的距离分开λ/2时的辐射效率设为η-(λ/2)[dB]时,所述玻璃板和所述天线配置成能够获得满足η-A≥η-0+(η-(λ/2)-η-0)×0.1的辐射效率η-A[dB]。(An antenna system is provided with: a glass plate having a thickness of 1.1mm or more and a dielectric loss tangent of 0.005 or more; and an antenna located at a position apart from one surface of the glass plate, wherein a ratio of power input to the antenna to power radiated into a space from the antenna is defined as radiation efficiency, a wavelength of a radio wave having a predetermined frequency of 10GHz or higher is defined as λ, and the glass plate is brought into contact with the antennaRadiation efficiency is set to η 0 [dB]Setting a radiation efficiency when the distance between the one surface and the antenna is divided by λ/2 to η λ/2 [dB]The glass plate and the antenna are configured so as to obtain a configuration satisfying eta A ≥η 0 +(η λ/2 ‑η 0 ) X 0.1 radiation efficiency eta A [dB]。)

1. An antenna system is provided with:

a glass plate having a thickness of 1.1mm or more and a dielectric loss tangent at 28GHz of 0.005 or more; and

an antenna located at a position separated from one surface of the glass plate,

the ratio of the power input to the antenna to the power radiated into space from the antenna is set as radiation efficiency,

effective wave of radio wave with frequency above 10GHzλ g, and η is the radiation efficiency when the glass plate is brought into contact with the antenna₀[dB]Setting radiation efficiency when the distance between the one surface and the antenna is divided by λ g/2 to η_λg/2[dB]The glass plate and the antenna are configured so as to satisfy

η_A≥η₀+(η_λg/2-η₀)×0.1

Radiation efficiency η_A[dB]。

2. The antenna system of claim 1,

the glass plate and the antenna are configured so that-10 [ dB ] can be obtained]The above radiation efficiency η_A。

3. The antenna system of claim 1 or 2,

the antenna is a planar antenna disposed in parallel with the one surface.

4. The antenna system of any of claims 1-3,

with a matching layer different from air between the glass plate and the antenna,

the matching layer has a dielectric loss tangent of 0.03 or less at 28 GHz.

5. The antenna system of claim 4,

the antenna includes a radiation section for radiating radio waves of the frequency, and an outer edge of the matching layer is located outside an outer edge of the radiation section in a plan view of the glass plate.

6. The antenna system of claim 5,

the outer edge of the matching layer is located outside the outer edge of the antenna in a plan view of the glass plate.

7. The antenna system of claim 5 or 6,

the radiating portion is a radiating plate made of a conductor material.

8. The antenna system of claim 5 or 6,

the radiating portion is a slit.

9. The antenna system of any one of claims 1-8,

a spacer having a relative dielectric constant different from that of air is provided between the glass plate and the antenna,

the spacer has a dielectric tangent at 28GHz of 0.03 or less.

10. The antenna system of claim 9,

the antenna includes a radiation portion that radiates radio waves of the frequency, and an outer edge of the spacer is located outside an outer edge of the radiation portion in a plan view of the glass plate.

11. The antenna system of claim 10,

the outer edge of the spacer is located outside the outer edge of the antenna in a plan view of the glass plate.

12. The antenna system of any of claims 9-11,

the spacer has a relative dielectric constant of 10 or less at 28 GHz.

13. The antenna system of any of claims 1-3,

the medium between the glass plate and the antenna is only air.

14. The antenna system of any one of claims 1-13,

the distance between the glass plate and the antenna is 2x λ 0 or less, where λ 0 is a wavelength in the air of a radio wave having a predetermined frequency of 10GHz or more.

15. The antenna system of any one of claims 1-14,

the antenna is an array antenna in which a plurality of antenna elements are arranged.

16. The antenna system of any one of claims 1-15,

the glass plate has a relative dielectric constant of 5 to 9 at 28 GHz.

17. The antenna system of any one of claims 1-16,

comprising an antenna with a transmission line having the antenna and a transmission line for supplying power to the antenna.

18. The antenna system of claim 17,

the antenna has a dielectric substrate and a dielectric layer,

the transmission line is provided on the first surface of the dielectric substrate,

a conductive plate is provided on a second surface of the dielectric substrate on the opposite side of the first surface,

the dielectric substrate has a thickness of 0.1 x λ 0 or less, where λ 0 is a wavelength in air of a radio wave having a predetermined frequency of 10GHz or more.

Technical Field

The present invention relates to antenna systems.

Background

In recent years, there is a trend toward the expansion of services in high-speed and high-capacity wireless communication systems using microwave and millimeter-wave frequency bands, such as the transition from 4G LTE to 5G (sub 6). Specifically, the service use band tends to be expanded from the 3GHz band to the 5 to 6GHz band. Further, an antenna that can cope with such a frequency band and has good directivity and reception sensitivity is required. V2X (Vehicle to electric communication technology), which is expected as Vehicle-to-Vehicle communication and road-to-Vehicle communication, is used in, for example, the ETC (Electronic Toll Collection) system in europe in the 5.9GHz band, and is used for various purposes. Further, attempts are also being made to spread to wireless communication systems using frequencies higher than sub6 (for example, 28GHz band, 40GHz band, 60GHz band, and 70GHz band).

In order to perform such communication in a high frequency band, for example, when transmission and reception are performed by a millimeter wave radar provided in a vehicle, attenuation of gain by a window glass, which has not been significant in communication in a conventional frequency band, may occur. In order to obtain a high gain, a configuration in which a radio wave transmitting material is embedded in a part of a window glass is disclosed (for example, see patent document 1).

Documents of the prior art

Patent document

Patent document 1: international publication No. 2017/188415

Disclosure of Invention

Problems to be solved by the invention

However, the technique of patent document 1 has a problem that the structure is complicated because the window glass itself is machined or a member separate from the window glass is included in a portion where the window glass normally exists.

Accordingly, the present disclosure provides an antenna system that uses a conventional glass plate having a thickness of 1.1mm or more and a dielectric loss tangent at 28GHz of 0.005 or more, and can transmit and receive radio waves in a predetermined high frequency band without complicating the structure of the glass plate.

Means for solving the problems

The present disclosure provides an antenna system including:

a glass plate having a thickness of 1.1mm or more and a dielectric loss tangent at 28GHz of 0.005 or more; and

an antenna located at a position separated from one surface of the glass plate,

the ratio of the power input to the antenna to the power radiated into space from the antenna is set as radiation efficiency,

λ g is an effective wavelength of a radio wave having a predetermined frequency of 10GHz or higher, and η is a radiation efficiency when the glass plate is brought into contact with the antenna₀[dB]Wherein the radiation efficiency when the distance between the one surface and the antenna is separated by λ g/2 is defined as η_λg/2[dB]The glass plate and the antenna are configured so as to satisfy

η_A≥η₀+(η_λg/2-η₀)×0.1

Radiation efficiency η_A[dB]。

Effects of the invention

According to the technique of the present disclosure, it is possible to provide an antenna system that uses a conventional glass plate having a thickness of 1.1mm or more and a dielectric loss tangent at 28GHz of 0.005 or more and can transmit and receive radio waves of a predetermined high frequency band without complicating the structure of the glass plate.

Drawings

Fig. 1 is a perspective view of an antenna system.

Fig. 2 is a front view of the antenna.

Fig. 3 is a side view of the antenna.

Fig. 4 is a perspective view of the antenna.

Fig. 5 is a cross-sectional view of the antenna.

Fig. 6A is a perspective view of an antenna with a transmission line.

Fig. 6B is a cross-sectional view of an antenna with a transmission line.

Fig. 7A is a perspective view of an antenna with a transmission line.

Fig. 7B is a cross-sectional view of an antenna with a transmission line.

Fig. 8A is a perspective view of an antenna with a transmission line.

Fig. 8B is a cross-sectional view of an antenna with a transmission line.

Fig. 9A is a perspective view of an antenna with a transmission line.

Fig. 9B is a cross-sectional view of an antenna with a transmission line.

Fig. 9C is a cross-sectional view of an antenna with a transmission line.

Fig. 10A is a perspective view of an antenna with a transmission line.

Fig. 10B is a cross-sectional view of an antenna with a transmission line.

Fig. 10C is a cross-sectional view of an antenna with a transmission line.

Fig. 11 is a diagram illustrating an antenna system including a plurality of antennas.

Fig. 12 is a configuration diagram showing a structure in which a matching layer and air exist between a glass plate and an antenna.

Fig. 13 is a configuration diagram showing a structure in which a matching layer exists between a glass plate and an antenna.

Fig. 14 is a configuration diagram showing a structure in which a matching layer and a spacer are present between a glass plate and an antenna.

Fig. 15 is a diagram illustrating an antenna system including an array antenna.

Fig. 16 is a diagram showing an example of a change in radiation efficiency with respect to a distance between a glass plate having a plate thickness of 2mm and an antenna.

Fig. 17 is a diagram showing an example of a change in radiation efficiency with respect to a distance between a glass plate having a plate thickness of 3mm and an antenna.

Fig. 18 is a diagram showing an example of a change in radiation efficiency with respect to a distance between a glass plate having a plate thickness of 4mm and an antenna.

Fig. 19 is a diagram showing an example of a change in radiation efficiency with respect to a distance between a glass plate having a plate thickness of 5mm and an antenna.

Fig. 20A is a configuration diagram showing a structure in which a matching layer exists between a glass plate and an antenna with a transmission line.

Fig. 20B is a perspective view showing a transmission line region in the antenna with a transmission line.

Fig. 21 is a diagram showing an example of a change in transmission loss of a transmission line with respect to the thickness of a dielectric base material.

Detailed Description

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each of the above-described embodiments, the directions parallel, orthogonal, horizontal, vertical, horizontal, and the like are allowed to deviate to such an extent that the effect of the present invention is not impaired. The X-axis direction, the Y-axis direction, and the Z-axis direction respectively indicate 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 each other. The XY plane, YZ plane, and ZX plane respectively represent an imaginary plane parallel to the X-axis direction and the Y-axis direction, an imaginary plane parallel to the Y-axis direction and the Z-axis direction, and an imaginary plane parallel to the Z-axis direction and the X-axis direction.

The antenna system of the present invention is not limited to the vehicle, and may be used in a building or an electronic device. In the following description of the embodiments of the present disclosure, the description will be given taking a vehicle as a representative example.

The vehicle antenna according to the embodiment of the present disclosure is suitable for transmission and reception of radio waves in a high frequency band (for example, 0.3GHz to 300GHz, particularly, 10GHz or more, for example, a band including 28GHz and a band including 39 GHz) such as microwaves and millimeter waves. The vehicle antenna according to the embodiment of the present disclosure can be applied to, for example, a V2X communication system, a 5 th generation mobile communication system (so-called 5G), a vehicle-mounted radar system, and the like, but applicable systems are not limited to these. An example of the V2X communication system is an etc (electronic Toll collection) system.

Fig. 1 is a perspective view illustrating an antenna system of an embodiment of the present disclosure. The antenna system 101 shown in fig. 1 includes a glass plate 70 for a window of a vehicle 80 and a vehicle antenna 110 (hereinafter, also simply referred to as "antenna 110") attached to the glass plate 70.

The glass plate 70 has a thickness (T) of 1.1mm or more and a dielectric loss tangent (tan. delta.) at 28GHz of 0.005 or more. The glass plate 70 is, for example, a front glass provided on the front side of the vehicle 80. The glass panel 70 is attached to a window frame on the front side of the vehicle 80 at a predetermined set angle θ with respect to the horizontal plane 90. The glass plate 70 has no particular upper limit of the thickness (T), and for example, a glass plate having a thickness of 5mm or less is generally used for 1 glass sheet for a vehicle. In the case of a laminated glass having a structure in which 2 sheets of glass are laminated, a glass plate having a maximum thickness of 10mm or less (5mm × 2) of the glass plate 70 is used. The thickness of the glass plate 70 may be 2mm or more, or 3mm or more depending on the application. In the case of laminated glass, the thickness may be, for example, 4mm or more (2mm or more × 2), or 6mm or more (3mm or more × 2).

The dielectric loss tangent (tan. delta.) is a value measured at 25 ℃ and 28GHz by a method specified in Japanese Industrial standards (JIS R1641: 2007) using a cavity resonator and a vector network analyzer. The value of the dielectric loss tangent (tan δ) in the present specification is a value measured at 25 ℃ and 28GHz in accordance with the above-mentioned specification, unless otherwise specified.

The composition of the glass constituting the glass plate 70 is not particularly limited, but a composition containing 50 to 80% of SiO in mol% based on oxides can be used₂0 to 10% of B₂O₃0.1 to 25% of Al₂O₃3 to 30% in total of Li₂O、Na₂O and K₂At least 1 basic metal oxide of the group consisting of O, 0-25% MgO, 0-25% CaO, 0-5% SrO, 0-5% BaO, and 0-5% ZrO₂And 0 to 5% of SnO₂A glass plate of (1).

The antenna 110 is located at a position separated from one surface of the glass plate 70. The antenna 110 is attached to the inside of the glass plate 70 via a member not shown such as a case so as to be located apart from the inner surface of the glass plate 70. In this example, the glass plate 70 is attached near the center of the upper region thereof. The number of antennas 110 mounted on the glass plate 70 is one in this example, but may be plural. When the wavelength of radio waves of a predetermined frequency of 10GHz or more transmitted and received by the antenna 110 in the air is λ 0, it is preferable from the viewpoint of height reduction if the distance D between one surface of the glass plate 70 and the antenna is 2 × λ 0 or less, more preferably 1.5 × λ 0 or less, and still more preferably 1.0 × λ 0 or less.

In this example, the antenna 110 is indirectly attached to the inner surface of the glass plate 70 via an attachment member not shown, but may be attached to another attachment site as long as it is disposed at a position separated from the inner surface of the glass plate 70. For example, the antenna 110 may be mounted on a ceiling portion in a vehicle interior, an indoor mirror, or the like. Even when the antenna 110 is mounted on such a mounting portion, the distance D may be 2 × λ 0 or less from the glass plate 70, more preferably 1.5 × λ 0 or less, and still more preferably 1.0 × λ 0 or less. In addition, when a matching layer or a spacer, which will be described later, is disposed between the glass plate 70 and the antenna 110, the distance D is also preferably within the above range.

Fig. 2 is a diagram showing the antenna in front view. Fig. 3 is a diagram showing the antenna in side view. The antenna 110 shown in fig. 2 and 3 is disposed at a position separated from the inner surface 76 of the glass plate 70. The glass plate 70 has an inboard surface 76 on the vehicle compartment side and an outboard surface 77 on the vehicle outboard side. The inner side surface 76 is a surface of the glass plate 70, and the outer side surface 77 is a surface opposite to the one surface. The plate thickness T represents the thickness of the glass plate 70, and is 1.1mm or more as described above.

Distance D is the shortest distance of inside surface 76 from antenna 110. In the case of fig. 3, the distance D represents the shortest distance between the radiation plate 20 and the inner side surface 76. Since the antenna 110 is disposed apart from the glass plate 70, the distance D is greater than zero. That is, distance D is zero, antenna 110 is in contact with inside surface 76. The antenna 110 may be disposed in parallel with the inner surface 76 or may be disposed in non-parallel with the inner surface 76, and the distance D represents the shortest distance between the radiation plate 20 and the inner surface 76 even when the antenna is disposed in non-parallel with the inner surface 76. That is, in the antenna 110, if the main radiation source of the radio wave is the surface of the radiation plate 20, the distance D may be the shortest distance between the radiation plate 20 and the inner surface 76 as described above. The radiation plate 20 is an example of a radiation plate that radiates a radio wave having a predetermined frequency of 10GHz or more, and in this specification, these are also referred to as "radiation sections 20" including slots that radiate radio waves having the same frequency.

Note that, in a mode in which the antenna 110 is located at a position away from one surface (the inner surface 76 in the case of fig. 3) of the glass plate 70, if a bonding member that bonds the antenna 110 to the one surface has a finite thickness, a mode in which a bonding member is interposed between the antenna 110 and the one surface is also included. That is, in this case, the (thinnest distance of the) thickness of the joining member corresponds to the distance D. Specific examples of the joining member include an adhesive, a bonding tape, and the like. In other words, the mode in which the antenna 110 is located at a position separated from one surface of the glass plate 70 includes a mode in which the antenna 110 is in contact with the one surface via an intervening member such as a bonding member.

Examples of the joining member include acrylic resins, rubbers, silicone resins, butadiene resins, epoxy resins, urethane resins, polyvinyl acetal resins, polyvinyl chloride resins, ionomers, polyester resins, ethylene-vinyl acetate copolymer resins, ethylene-ethyl acrylic copolymer resins, polycycloolefin resins, and the like, and 1 of them may be used, or 2 or more thereof may be used in combination.

Here, the ratio of the power input to the antenna 110 to the power radiated into the space from the antenna 110 is defined as the radiation efficiency. The power input to the antenna 110 means the power received by the antenna 110 out of the power supplied to the antenna 110. Therefore, power lost in a transmission line such as a coaxial cable or a microstrip line connected to the antenna 110 is not included in the "power input to the antenna 110". As a result of the studies by the present inventors, it was found that the radiation efficiency has a relationship with the sheet thickness T and the distance D.

Further, λ g is an effective wavelength of a radio wave having a predetermined frequency of 10GHz or more, but the effective wavelength λ g is the same as the wavelength λ 0 in vacuum when the medium from the antenna 110 to the glass plate 70 is air (λ g ═ λ 0). However, when a dielectric or a dielectric and a metal, which will be described later, such as a matching layer or a spacer is present between the antenna 110 and the glass plate 70 in addition to air, the effective wavelength λ g means a wavelength in consideration of the wavelength shortening rate of these materials. Further, the matching layer and the spacer may be formed by coating such as dry coating or wet coating.

Here, the radiation efficiency when the glass plate 70 is brought into contact with the antenna 110 (when D is 0) is η₀[dB]. Further, let η be the radiation efficiency when the distance between one surface of the glass plate 70 and the antenna 110 is set to λ g/2 (when D is λ g/2)_λg/2[dB]. The inventors have found that if the glass plate 70 and the antenna 110 are configured to obtain a configuration satisfying "η_A≥η₀+(η_λg/2-η₀) X 0.1 ″, radiation efficiency [. eta ]_A[dB]The glass plate 70 can transmit and receive radio waves of a high frequency band of 10GHz or more without being processed. In addition, radiation efficiency η_APreferably satisfies "η_A≥η₀+(η_λg/2-η₀) 0.2 ", more preferably satisfies" η_A≥η₀+(η_λg/2-η₀) 0.3'. The "glass plate 70 is not processed" may be exemplified by a case where the glass plate 70 itself in the vicinity of the antenna 110 is not processed to be locally reduced in thickness or the like, and generally means that the state of the glass itself or the laminated glass used is maintained.

In addition, the inventors have discovered that-10 [ dB ] can be achieved if the glass plate 70 and antenna 110 are configured such that]Above thatRadiation efficiency eta_AThe glass plate 70 can transmit and receive radio waves of a high frequency band of 10GHz or more without being processed. The inventors have found that a preferred-7 dB can be achieved if the glass plate 70 and antenna 110 are configured to achieve]More than, more preferably-5 [ dB ]]Above, further preferably-3 [ dB ]]More than, still more preferably-1 [ dB ]]The above radiation efficiency η_AThe glass plate 70 can transmit and receive radio waves of a high frequency band of 10GHz or more without being processed.

Next, a configuration example of the antenna 110 will be described in detail. The antenna 110 shown in fig. 2 and 3 includes at least a conductor plate 10 and a radiation plate 20.

Typically, the conductive plate 10 is a planar layer whose surface is parallel to the XY plane, and functions as a ground of the antenna 110. The conductor plate 10 is a plate-like or film-like conductor. Examples of the material of the conductor used for the conductor plate 10 include, but are not limited to, silver, copper, and the like. The shape (as viewed from the Z-axis direction) of the illustrated conductive plate 10 is a square in a plan view, but may be a polygon other than a square, or may be another shape such as a circle. The "plate-like or film-like" referred to herein may have a 3-dimensional shape, and includes, for example, a convex shape, a concave shape, and a wavy shape, and is also similar to a radiation plate and a dielectric substrate which will be described later. However, the "plate-like shape or film-like shape" described above is preferably a planar shape (2-dimensional shape) in that predetermined antenna gain characteristics can be easily predicted.

The radiation plate 20 is a plate-like or film-like conductor disposed to face the conductive plate 10 in the Z-axis direction, and has a smaller area than the conductive plate 10. The radiation plate 20 is a planar layer having a surface parallel to the XY plane, and functions as a radiation element of the antenna 110. Examples of the material of the conductor used for the radiation plate 20 include, but are not limited to, silver, copper, and the like. The shape (as viewed from the Z-axis direction) of the illustrated radiation plate 20 is a square in plan view, but may be a polygon other than a square, or may be another shape such as a circle.

The radiation plate 20 is disposed separately from the conductor plate 10. The medium between the conductor plate 10 and the radiation plate 20 includes at least one of a space and a dielectric base material. Fig. 2 and 3 show a case where the medium is composed of only the dielectric base material 60. When the medium is a space (air), the radiation plate 20 and the conductor plate 10 may be fixed by a case (not shown) as needed.

The dielectric substrate 60 is a plate-like or film-like dielectric layer mainly composed of a dielectric substance. The dielectric substrate 60 has a first surface 61 and a second surface 62 opposite the first surface 61. The surfaces 61, 62 are parallel to the XY plane. The radiation plate 20 is provided on a surface 61 which is one surface of the dielectric substrate 60, and the conductor plate 10 is provided on a surface 62 which is the other surface of the dielectric substrate 60.

The dielectric substrate 60 may be a dielectric substrate such as a glass epoxy plate, or may be a dielectric sheet. Examples of the material of the dielectric used for the dielectric substrate 60 include, but are not limited to, glass such as quartz glass, ceramics, fluorine-based resins such as polytetrafluoroethylene, liquid crystal polymers, and cycloolefin polymers. When the dielectric substrate 60 is a resin material, an ultraviolet absorbing layer may be applied to the surface of the resin or an ultraviolet absorber may be added to the resin material in order to improve ultraviolet resistance.

The antenna 110 is, for example, a planar antenna disposed in parallel with respect to the inner side surface 76. By arranging the antenna 110 as a planar antenna in parallel with the inner surface 76 inclined with respect to the horizontal plane 90 (see fig. 1), mounting is facilitated, and the bottom height is facilitated.

The antenna 110 is, for example, a planar antenna including a dielectric substrate 60, a radiation plate 20 provided on the first surface 61, and a conductor plate 10 facing the radiation plate 20 with the dielectric substrate 60 interposed therebetween. A planar antenna having such a structure is called a patch antenna or a microstrip antenna.

Fig. 4 is a perspective view showing an antenna 110 including a dielectric substrate 60 on which a conductor plate 10 and a radiation plate 20 are formed. Fig. 5 is a cross-sectional view showing an antenna 110 including a dielectric substrate 60 on which a conductor plate 10 and a radiation plate 20 are formed. The antenna 110 includes a connection conductor 40 that connects the feeding portion 30 and the radiation plate 20 so as to penetrate a part of the dielectric substrate 60.

The feeding unit 30 is a portion to which power is fed in a contact or non-contact manner, and is a portion to which one end of a transmission line, not shown, is connected or close. Specific examples of the transmission line include a coaxial cable and a microstrip line. The other end of the transmission line is connected to a communication device that communicates with the outside of the vehicle using the antenna 110. The feeding portion 30 is located on the side where the conductor plate 10 is arranged with respect to the radiation plate 20.

The connection conductor 40 is not in contact with the conductor plate 10. The connection conductor 40 has one end connected to the power supply portion 30 and the other end connected to the radiation plate 20 at the connection point 22. The connection point 22 is offset from the center of gravity 21 of the radiation plate 20, and is located on the negative side in the Y-axis direction with respect to the center of gravity 21 in the illustrated case. The center of gravity 21 corresponds to the center of a symmetrical pattern such as a square in the radiation plate 20.

Specific examples of the connection conductor 40 include a conductor formed inside a through hole penetrating the dielectric base material 60 in the Z-axis direction, a core wire of a coaxial cable, a conductor pin formed in a pin shape, and the like, but the connection conductor 40 is not limited to these. When the medium between the conductor plate 10 and the radiation plate 20 includes a space, specific examples of the connection conductor 40 include a core wire of a coaxial cable, a conductor pin, and the like, but the connection conductor 40 is not limited to these.

As shown in fig. 5, when viewed from the radiation plate 20 side with respect to the conductor plate 10, the center of gravity 21 of the radiation plate 20 overlaps the center of gravity 11 of the conductor plate 10, which is preferable in terms of improving the antenna gain of the antenna 110 in the direction from the conductor plate 10 side toward the radiation plate 20 side. In this example, the viewpoint from the radiation plate 20 side with respect to the conductive plate 10 indicates the viewpoint from the positive side in the Z-axis direction, and the direction from the conductive plate 10 side toward the radiation plate 20 side indicates the direction toward the positive side in the Z-axis direction.

As described above, the coaxial cable and the microstrip line are exemplified as the transmission line to the planar antenna, but the transmission line will be described more specifically. In addition, in this specification, a component including a planar antenna and a transmission line is referred to as an "antenna with a transmission line".

Fig. 6A is a perspective view showing the antenna 201 with a transmission line, and fig. 6B is a sectional view of Y1-Y1'. The antenna 201 with a transmission line includes a dielectric substrate 60, a radiation plate 20 provided on a first surface 61 of the dielectric substrate 60, and a microstrip line 24 connected to the radiation plate 20 provided on the first surface 61. The antenna 201 with a transmission line includes the conductor plate 10 on the second surface 62 of the dielectric substrate 60 opposite to the first surface 61, and functions as a ground. The dielectric base material 60 (the first dielectric base material 60a and the second dielectric base material 60b described later) has a small dielectric loss tangent (tan δ), and can reduce the transmission loss in the transmission line. The dielectric loss tangent (tan δ) of the dielectric substrate 60 may be 0.03 or less, more preferably 0.008 or less, and still more preferably 0.001 or less.

In the antenna 201 with a transmission line, the thinner the thickness of the dielectric substrate 60 is, the more the radiation loss from the transmission line can be suppressed, so that the transmission loss due to the microstrip line 24 can be reduced more easily, and particularly, the effect of reducing the transmission loss becomes more remarkable at a high frequency. However, as compared with the case where air is present between the radiation plate 20 (antenna 110) and the glass plate 70 as shown in fig. 3, in the case where the matching layer 74 is provided between the radiation plate 20 (antenna 110) and the glass plate 70 or the matching layer 74 and the spacer 75 are provided as shown in fig. 12 to 14 described later, the radiation loss from the transmission line can be suppressed as the thickness of the dielectric substrate 60 is reduced. Therefore, in the case of a structure including the matching layer 74 between the radiation plate 20 (antenna 110) and the glass plate 70 or a structure including the matching layer 74 and the spacer 75, the transmission loss due to the microstrip line 24 is more easily reduced as the thickness of the dielectric substrate 60 is reduced. The thickness of the dielectric substrate 60 may be 0.1 × λ 0 or less, preferably 0.08 × λ 0 or less, and more preferably 0.06 × λ 0 or less. The thickness of the dielectric substrate 60 is not particularly limited, but may be 0.01mm or more from the viewpoint of processing.

Fig. 7A is a perspective view showing the antenna 202 with a transmission line, and fig. 7B is a sectional view of Y2-Y2'. The antenna 202 with a transmission line includes a first dielectric substrate 60a, a second dielectric substrate 60b, a radiation plate 20, a conductor plate 10, a connection conductor 40, and a microstrip line 25. The first dielectric base material 60a and the second dielectric base material 60b are arranged so as to overlap in the thickness direction. The first dielectric substrate 60a has a first surface 61 on the opposite side from the second dielectric substrate 60b and a second surface 62 on the side of the second dielectric substrate 60b, and the second dielectric substrate 60b has a third surface 63 on the side of the first dielectric substrate 60a and a fourth surface 64 on the opposite side from the first dielectric substrate 60 a. The first dielectric substrate 60a and the second dielectric substrate 60b may be different materials or the same material.

The antenna 202 with a transmission line has a radiation plate 20 provided on the first surface 61, a connection conductor 40 connected to the radiation plate 20, and a microstrip line 25 connected to the connection conductor 40. The antenna 202 with a transmission line includes the conductive plate 10 between the first dielectric base 60a and the second dielectric base 60b and on the second surface 62 and the third surface 63, and functions as a ground. The connection conductor 40 is a conductor extending in the thickness direction (Z-axis direction) of the first dielectric base material 60a and the second dielectric base material 60b and formed inside a through hole penetrating the first dielectric base material 60a, the conductor plate 10, and the second dielectric base material 60b, and is not connected to at least the conductor plate 10. Also, the microstrip line 25 is provided on the fourth surface 64.

In the antenna 202 with a transmission line, the microstrip line 25 is provided on the opposite side (negative Z-axis direction) to the radiation plate 20 side with respect to the conductor plate 10. Therefore, in the antenna 202 with a transmission line, the microstrip line 25 can reduce the transmission loss of the microstrip line 25 due to the glass plate 70 and the dielectric not shown provided between the radiation plate 20 and the glass plate 70.

Fig. 8A is a perspective view showing the antenna 203 with a transmission line, and fig. 8B is a sectional view of Y3-Y3'. The antenna with transmission line 203 includes a first dielectric substrate 60a, a second dielectric substrate 60b, a slot 20a, a first conductor plate 10a, a second conductor plate 10b, and a strip line 26. The first dielectric base material 60a and the second dielectric base material 60b are arranged so as to overlap in the thickness direction. The first dielectric substrate 60a has a first surface 61 on the opposite side from the second dielectric substrate 60b and a second surface 62 on the side of the second dielectric substrate 60b, and the second dielectric substrate 60b has a third surface 63 on the side of the first dielectric substrate 60a and a fourth surface 64 on the opposite side from the first dielectric substrate 60 a. The first dielectric substrate 60a and the second dielectric substrate 60b may be different materials or the same material. In the antenna with transmission line 203, the slot 20a corresponds to the "radiation section 20".

The antenna with transmission line 203 has a strip line 26 disposed between the second surface 62 and the third surface 63. The antenna 203 with a transmission line includes the first conductive plate 10a on the first surface 61 so as to overlap at least a part of the strip line 26 when viewed in the thickness direction (Z-axis direction) of the first dielectric base 60a and the second dielectric base 60b, and functions as a ground. The antenna 203 with a transmission line is a so-called slot antenna including a slot 20a having an opening formed in a part of the first conductive plate 10 a. The slit 20a may overlap at least a part (e.g., a tip portion) of the strip line 26 in a plan view of the first conductor plate 10 a. The slit 20a may be formed by a recess portion exposing the first surface 61, and in this case, the medium forming the recess portion of the slit 20a is air, but the recess portion may be filled with a dielectric material other than air. The antenna 203 with a transmission line includes the second conductive plate 10b on the fourth surface 64 so as to overlap the slot 20a and the strip line 26 when viewed in the thickness direction (Z-axis direction) of the first dielectric base material 60a and the second dielectric base material 60b, and functions as a ground.

In the antenna with transmission line 203, since the strip line 26 is disposed between the first conductor plate 10a and the second conductor plate 10b as viewed from the Z-axis direction, the transmission loss of the strip line 26 due to the dielectric and the glass plate 70, not shown, provided between the first conductor plate 10a and the glass plate 70 can be reduced.

Fig. 9A is a perspective view showing the antenna 204 with a transmission line, fig. 9B is a sectional view of Y4-Y4 ', and fig. 9C is a sectional view of Y5-Y5'. The antenna 204 with a transmission line has a form in which a transmission line of a signal functions as a Substrate Integrated Waveguide (SIW). The antenna with transmission line 204 includes a first surface 61, a (first) dielectric base material 60a facing the first surface 61, a first conductive plate 27a provided on the first surface 61, and a second conductive plate 27b provided on the second surface 62. The antenna with transmission line 204 is a so-called slot antenna including a slot 20a having an opening formed in a part of the first conductive plate 27 a. As in the case of the antenna 204 with a transmission line, the slot 20a may be filled with air or a dielectric material other than air.

The antenna with transmission line 204 includes conductive walls 28a, 28b, and 28c made of a conductive material extending in the thickness direction of the dielectric substrate 60a and connecting the first conductive plate 27a and the second conductive plate 27 b. The antenna with transmission line 204 shown in fig. 9A includes a plurality of (a plurality of) conductor walls 28a arranged at a constant interval in the Y-axis direction, a plurality of (a plurality of) conductor walls 28b arranged substantially parallel to the (a plurality of) conductor walls 28a, and a plurality of (a plurality of) conductor walls 28c arranged at a constant interval in the X-axis direction so as to surround the slot 20a, as viewed from the thickness direction (Z-axis direction) of the dielectric base material 60 a. That is, the transmission line in the antenna with transmission line 204 corresponds to the dielectric base material 60a located between the conductor wall(s) 28a, the conductor wall(s) 28b, and the conductor wall(s) 28 c. The conductor wall 28a, the conductor wall 28b, and the conductor wall 28c are also collectively referred to as "conductor walls 28", and the conductor walls 28 are arranged in a U shape so as to surround the slot 20a when viewed from the thickness direction (Z-axis direction) of the dielectric base 60 a.

The antenna 204 with a transmission line includes conductive plates (a first conductive plate 27a and a second conductive plate 27b) provided on both main surfaces of the dielectric substrate 60a, and a conductive wall 28 connecting the two conductive plates in the thickness direction of the dielectric substrate 60 a. By providing the conductive plates (the first conductive plate 27a and the second conductive plate 27b) and the conductive wall 28, it is possible to reduce the transmission loss of the transmission line provided in the dielectric substrate 60a, which is caused by the glass plate 70 and the dielectric (not shown) provided between the first conductive plate 27a and the glass plate 70.

Fig. 10A is a perspective view showing the antenna 205 with a transmission line, fig. 10B is a sectional view of Y6-Y6 ', and fig. 10C is a sectional view of Y7-Y7'. The antenna with transmission line 205 includes additional elements in the antenna with transmission line 204, and description thereof is omitted in a part overlapping with the description of the antenna with transmission line 204.

The antenna 205 with a transmission line includes the second dielectric base material 60b and the slot 20a as the additional elements described above. The first dielectric base material 60a and the second dielectric base material 60b are arranged so as to overlap in the thickness direction. The first dielectric substrate 60a has a first surface 61 on the side of the second dielectric substrate 60b and a second surface 62 on the opposite side of the second dielectric substrate 60b, and the second dielectric substrate 60b has a third surface 63 on the opposite side of the first dielectric substrate 60a and a fourth surface 64 on the side of the first dielectric substrate 60 a. The first dielectric substrate 60a and the second dielectric substrate 60b may be different materials or the same material.

Specifically, the second dielectric substrate 60b includes the radiation plate 20 on the third surface 63 and the first conductor plate 27a on the fourth surface 64. The radiation plate 20 is provided at a position close to the slit 20a as viewed in the thickness direction (Z-axis direction) of the first dielectric substrate 60a and the second dielectric substrate. Similarly to the antenna 204 with a transmission line, the antenna 205 with a transmission line also includes conductive plates (the first conductive plate 27a and the second conductive plate 27b) provided on both main surfaces of the first dielectric substrate 60a, and a conductive wall 28 connecting the conductive plates in the thickness direction of the first dielectric substrate 60 a. By providing the conductive plates (the first conductive plate 27a and the second conductive plate 27b) and the conductive wall 28, the transmission loss of the transmission line provided in the first dielectric substrate 60a, which is caused by the glass plate 70 and the dielectric (not shown) provided between the radiation plate 20 and the glass plate 70, can be reduced. In the antenna 205 with a transmission line, the radiation portion corresponds to the radiation plate 20.

As the transmission line, a Coplanar line with ground (CBCPW: Conductor Back Coplanar Waveguide), a column Wall Waveguide (PWW: Post Wall Waveguide), a parallel double line type line (CPS: Coplanar Strip), and a slot line may be used in addition to the transmission line.

Fig. 11 is a partial cross-sectional view illustrating a vehicle antenna system including a plurality of antennas (antennas with transmission lines). The antenna system 100 shown in fig. 11 includes a front glass 71, a rear glass 72, a front antenna 111 mounted on the front glass 71, and a rear antenna 112 mounted on the rear glass 72. The front glass 71 and the rear glass 72 are examples of the glass plate 70, and the front antenna 111 and the rear antenna 112 are examples of the antenna 110. The front antenna 111 exemplifies a first antenna, and the rear antenna 112 exemplifies a second antenna.

The radiation plate 20 of the front antenna 111 is disposed at a predetermined inclination angle α with respect to a vertical plane 91 perpendicular to the horizontal plane 90. In this case, the front antenna 111 can be easily mounted and the bottom height can be easily increased by adjusting the inclination angle α so that the radiation plate 20 is parallel to the inner surface of the front glass 71.

Similarly, the radiation plate 20 of the rear antenna 112 is disposed at a predetermined inclination angle α with respect to a vertical plane 91 perpendicular to the horizontal plane 90. In this case, by adjusting the inclination angle α so that the radiation plate 20 is parallel to the inner surface of the rear glass 72, the rear antenna 112 can be easily mounted, and the bottom height can be easily increased.

In fig. 11, the front antenna 111 is mounted apart from one surface of the front glass 71 so that the radiation plate 20 is positioned on the vehicle front side with respect to the conductor plate 10. On the other hand, the rear antenna 112 is mounted separately from one surface of the rear glass 72 so that the radiation plate 20 is positioned on the vehicle rear side with respect to the conductor plate 10. By mounting the front antenna 111 and the rear antenna 112 in this manner, the front antenna 111 can secure the antenna gain in the region in front of the vehicle, and the rear antenna 112 can secure the antenna gain in the region behind the vehicle. Therefore, the antenna gain in the front-rear direction of the vehicle 80 can be ensured.

The conductive plate 10 of the front antenna 111 is disposed at a predetermined inclination angle γ with respect to a vertical plane 91 perpendicular to the horizontal plane 90. In this case, the inclination angle γ is adjusted so that the conductor plate 10 is parallel to the inner surface of the front glass 71, whereby the front antenna 111 can be easily mounted and the bottom height can be easily increased. The same applies to the inclination angle γ of the conductor plate 10 of the rear antenna 112.

The inclination of 0 ° with respect to the vertical plane 91 means that the inclination is parallel to the vertical plane 91.

In the antenna system 100 shown in fig. 11, one vehicle antenna (antenna with a transmission line) is attached to each of the front glass 71 and the rear glass 72. However, the vehicle antenna system 100 may include at least 2 window glasses out of the front glass 71, the rear glass 72, and the side glass 73, and at least one vehicle antenna (antenna with a transmission line) attached to each of the at least 2 window glasses. The antenna system 100 may include a plurality of antennas on the front glass 71, or may include a plurality of antennas (antennas with transmission lines) on the rear glass 72.

Fig. 12 is a configuration diagram (schematic cross-sectional view of YZ plane) showing a structure in which the matching layer 74 and the air 92 are present between the glass plate 70 and the antenna 110. By matching the impedance with the matching layer 74, the transmittance of the radio wave transmitted through the glass plate 70 and the matching layer 74 can be increased. Matching layer 74 is in contact with one side of glass plate 70. The matching layer 74 is not limited to a structure in which it is in contact with the inner surface of the glass plate 70 with an adhesive, and may be in contact with the inner surface of the glass plate 70 without an adhesive via a mounting member such as a bracket, not shown. In the cross-sectional view (YZ plane) in fig. 12, the matching layer 74 exhibits a certain thickness, i.e., a rectangular shape, but is not limited thereto. Matching layer 74 may also be triangular, trapezoidal, etc. in cross-section, with non-parallel faces between the inside surface 76 of glass plate 70 and antenna 110. The matching layer 74 may be a dielectric lens having a shape such as a flat convex shape or a flat concave shape. By providing the matching layer 74 with a distribution in its thickness in this way, the directivity of the antenna can be adjusted to meet a desired specification. The arrangement in which the matching layer 74 has a distribution in its thickness is not limited to fig. 12, and may be applied to the description of fig. 13 and 14 to be described later.

The matching layer 74 may have a structure in which the outer edge of the glass plate 70 in a plan view is located outside the outer edge of the radiation section 20 (the radiation plate 20 or the slit 20 a). This is because the radio wave from the radiation section (the radiation plate 20 or the slit 20a) is radiated not only in the thickness direction (Z-axis direction) of the matching layer 74 but also at a predetermined divergence angle with respect to the thickness direction, and therefore, the effect of the matching layer 74 is exhibited also in the direction of the radio wave radiated at such an angle. The matching layer 74 may have a structure in which the outer edge of the glass plate 70 in a plan view is located outside the outer edge of the antenna 110.

The material of the matching layer 74 is not particularly limited, but an organic material such as resin or an inorganic material such as glass can be used. When the matching layer 74 is a resin, examples thereof include a polyethylene terephthalate (PET) resin, a cycloolefin resin (COP), an acrylic resin, an ABS resin, a polycarbonate resin, a vinyl chloride resin, and the like. Among them, a cycloolefin resin can be suitably used for the matching layer 74 from the viewpoint of heat resistance. When the matching layer 74 is made of a resin material, an ultraviolet absorbing layer may be applied to the surface of the resin material or an ultraviolet absorber may be added to the resin material in order to improve ultraviolet resistance.

The dielectric loss tangent (tan δ) of the matching layer 74 is preferably 0.03 or less, and the gain of the antenna 110 can be improved as compared with the case where the dielectric loss tangent (tan δ) exceeds 0.03. In addition, the dielectric loss tangent (tan δ) of the matching layer 74 is more preferably 0.02 or less, and still more preferably 0.01 or less, in order to further increase the gain of the antenna 110. The lower limit value of the dielectric loss tangent (tan δ) of the matching layer 74 may be larger than zero (that is, the dielectric loss tangent (tan δ) of air).

The matching layer 74 is not limited to being formed only of a dielectric, and may include a metamaterial in which a plurality of metal patterns are coated with a resin, or the matching layer 74 itself may be formed of a metamaterial. The metamaterial can be used to arbitrarily design a dielectric constant and a magnetic permeability for a specific wavelength, and by applying this, the directivity of the antenna 110 can be adjusted to conform to a desired specification. When the matching layer 74 includes a dielectric and a metamaterial, the metamaterial may be provided on the inner surface 76 side of the glass plate 70 with respect to the dielectric, or may be provided on the antenna 110 side with respect to the dielectric. When the spacers 75 described later are present, the metamaterial may be disposed on the surfaces of the spacers 75.

The metamaterial may have a structure in which active control for changing the dielectric constant of a metal pattern, for example, can be performed using an electric control circuit. In this way, by configuring the metamaterial to be capable of active control, the directivity of the antenna 110 can be adjusted to a desired state according to the situation.

The matching layer 74 is not limited to being formed only of a dielectric, and may include a director. The directivity of the antenna 110 can be adjusted by controlling the phase of the radio wave by the director.

The matching layer 74 is not limited to being formed only of a dielectric material, and may include a Frequency Selective Surface (FSS) formed of a conductor (metal) pattern, or the matching layer 74 itself may be formed of a Frequency Selective Surface. The frequency selective surface has an opening (not having a conductor) on the conductor surface, and can selectively transmit a radio wave of a predetermined frequency according to the pattern of the opening, so that a predetermined frequency to be transmitted to and received from the antenna 110 can be further selected to be within a desired range. In the case where the matching layer 74 includes a dielectric and a frequency selective surface, the frequency selective surface may be provided on the inner surface 76 side of the glass plate 70 with respect to the dielectric, or may be provided on the antenna 110 side with respect to the dielectric. When the spacer 75 described later is present, the frequency selective surface may be disposed on the surface of the spacer 75. Further, by matching the impedance using the frequency selective surface, the transmittance of the radio wave transmitted through the glass plate 70 and the matching layer 74 can be increased.

Fig. 13 is a configuration diagram showing a structure in which the matching layer 74 is present between the glass plate 70 and the antenna 110. In fig. 13, there is no air between the glass plate 70 and the antenna 110. Matching layer 74 has a first matching surface in contact with one side of glass plate 70 and a second matching surface in contact with antenna 110. Suitable ranges for the dielectric loss tangent of the matching layer 74 are the same as described above. In fig. 13, the matching layer 74 is shown as the same region as the antenna 110 in a plan view (as viewed in the Z-axis direction) of the glass plate 70, but the matching layer 74 may have a structure having a region in which the outer edge in a plan view is located outside the outer edge of the radiation section 20 (the radiation plate 20 or the slit 20a) for the same reason as that described in fig. 12. The matching layer 74 may have a region with an outer edge located outside the outer edge of the antenna 110 in a plan view.

Fig. 14 is a configuration diagram showing a structure in which the matching layer 74 and the spacer 75 are present between the glass plate 70 and the antenna 110. In fig. 14, air is not present between the glass plate 70 and the antenna 110, but air may be present. In addition, the matching layer 74 may be absent. Matching layer 74 has a first matching surface in contact with one side of glass plate 70 and a second matching surface in contact with spacer 75. Suitable ranges for the dielectric loss tangent of the matching layer 74 are the same as described above. The spacer 75 is a distance adjustment member for adjusting the distance from the glass plate 70 to the antenna 110. The spacer 75 may have a shape capable of adjusting a distance and may also function as a proximity matching layer by using a material capable of adjusting impedance. The spacer 75 illustrated in fig. 14 has a first spacer face in contact with the matching layer 74 and a second spacer face in contact with the antenna 110. However, the spacer 75 is not limited to the embodiment shown in fig. 14, and may have a tubular structure having a predetermined thickness around the periphery thereof and a through hole formed in the center thereof.

In fig. 14, for the same reason as described in fig. 12, the spacer 75 and the matching layer 74 may be configured to have a region in which the outer edge of the glass plate 70 (as viewed in the Z-axis direction) is located outside the radiation section (the radiation plate 20 or the slit 20a) in a plan view. That is, the radio wave from (the radiation plate 20 of) the antenna 110 is radiated not only in the thickness direction (Z-axis direction) of the spacer 75 and the matching layer 74 but also at a predetermined divergence angle with respect to the thickness direction. Therefore, even in the direction of the radio wave radiated at such an angle, the radiation efficiency can be improved by providing the spacer 75 and the matching layer 74. The spacer 75 and the matching layer 74 may have a structure having an outer edge located outside the outer edge of the antenna 110 in a plan view.

The dielectric tangent (tan δ) of the spacer 75 is preferably 0.03 or less, and the gain of the antenna 110 can be improved as compared with the case where the dielectric tangent (tan δ) exceeds 0.03. In addition, in order to further increase the gain of the antenna 110, the dielectric tangent (tan δ) of the spacer 75 is more preferably 0.02 or less, and still more preferably 0.01 or less. The lower limit value of the dielectric tangent (tan δ) of the spacer 75 may be larger than zero (that is, the dielectric tangent (tan δ) of air).

The material of the spacer 75 is not particularly limited, but as in the matching layer 74 described above, an organic material such as a resin or an inorganic material such as glass can be used. In the case where the spacer 75 is made of a resin material, similarly to the matching layer 74, an ultraviolet absorbing layer may be applied to the surface of the resin material or an ultraviolet absorber may be added to the resin material in order to improve ultraviolet resistance.

If the relative dielectric constant of the spacer 75 is 10 or less, the gain of the antenna 110 can be ensured. In addition, when the relative permittivity of the spacer 75 is equal to or less than the relative permittivity of the glass plate 70, the antenna 110 can be designed more easily than when the relative permittivity of the glass plate 70 is exceeded. For example, since the relative permittivity of the glass plate 70 is 5 or more and 9 or less, the relative permittivity of the spacer 75 is preferably 1.5 or more and 7 or less, and more preferably 2 or more and 5 or less. In addition, the relative dielectric constant refers to a value at a frequency of 28GHz, unless otherwise specified in the present specification.

Fig. 15 is a diagram illustrating an antenna system including an array antenna. The antenna (antenna with a transmission line) located at a position separated from one surface of the glass plate 70 may be an array antenna in which a plurality of antenna elements are arranged. In fig. 15, an array antenna 113 in which 4 antenna elements 20A, 20B, 20C, 20D are arranged in the Y-axis direction is shown. The array antenna 113 includes a plurality of antennas in an array form, which have the same configuration as the antenna 110 described above. The antenna elements 20A, 20B, 20C, and 20D have the same configuration as the radiation plate 20 or the slit 20A described above. The power feeding portions 30A, 30B, 30C, and 30D have the same configuration as the power feeding portion 30 described above.

By using an antenna (antenna with a transmission line) located at a position separated from one surface of the glass plate 70 as an array antenna in which a plurality of antenna elements are arranged, the radiation range of the antenna (directivity of the antenna) can be expanded.

FIGS. 16 to 19 show radiation efficiencies η of distances D between the antenna 110 and the glass plate 70 having plate thicknesses T of 2, 3, 4 and 5mm under a radio wave of 28GHz_AAn example of the change of (1). Fig. 16 to 19 show data measured in simulation. Further, the medium at the distance D is air. In this case, in simulation, the unit of the size of each part of the antenna 110 shown in fig. 4 and the like is mm, and the unit is represented by mm

L60：10

L61：10

L62：0.2

L20：2.6

L21：2.6。

The shortest distance from the connection point 22 to one side of the square-shaped radiation plate 20 is 0.9 mm. The relative dielectric constant of the dielectric substrate 60 at 28GHz radio wave was 3.79. The simulated glass plate 70 had a square shape of 50mm in length and 50mm in width. The glass plate 70 had a relative dielectric constant of 6.8 and a dielectric loss tangent of 0.01 at a radio wave of 28 GHz. At this time, a simulation was performed under the condition that the surface of the radiation plate 20 and the inner surface of the glass plate 70 are arranged in parallel, and the distance therebetween becomes the distance D at any position.

Referring to FIGS. 16 to 19, it is shown that the shorter the distance D, the radiation efficiency eta_AThe lower the tendency. In addition, radiation efficiency η_AThe degree of reduction in (D) is larger as the plate thickness T is larger when compared at the same distance D. The measured data shown in FIGS. 16 to 19 satisfy the above-mentioned "η_A≥η₀+(η_λg/2-η₀) X 0.1 ″, radiation efficiency [. eta ]_A. Further, fig. 16 to 19 show characteristics of radio waves having a frequency of 28GHz, but the higher the frequency, the shorter the wavelength, and therefore, "η_A≥η₀+(η_λg/2-η₀) The smaller the value of distance D is for x 0.1 ". That is, when the frequency of the transmitted/received radio wave is high, the distance D can be reduced, and therefore, the distance D can be reducedThe antenna 110 is brought close to the glass plate 70, and the bottom height of the antenna system can be easily increased.

Next, a simulation model relating to the loss of the transmission line (transmission loss) in the antenna with the transmission line will be described based on fig. 20A and 20B. Fig. 20A shows a structure in which an antenna 201 with a transmission line is mounted on a glass plate 70 via a matching layer 74, and includes a first bonding member 51 that connects the antenna 201 with the transmission line and the matching layer 74, and a second bonding member 52 that connects the glass plate 70 and the matching layer 74. In fig. 20A, the region a is a region including a planar antenna in the antenna with transmission line 201, and the region B is a region including a transmission line in the antenna with transmission line 201. That is, the antenna with transmission line 201 includes an antenna region 201a included in the region a and a transmission line region 201B included in the region B.

Fig. 20B is a perspective view of only the transmission line region 201B of the antenna with transmission line 201 in the region B. The transmission line region 201b includes a dielectric substrate 60, a microstrip line 24 serving as a transmission line on the first surface 61 side of the dielectric substrate 60, and a conductor plate 10 functioning as a ground on the second surface 62 side. In the present simulation model, in the region B, that is, in the structure in which the transmission line region 201B of the antenna with transmission line 201, the first bonding member 51, the matching layer 74, the second bonding member 52, and the glass plate 70 are sequentially stacked, the transmission characteristics of the transmission line with respect to the frequency (S21) were simulated under the same conditions except that the thickness (t) of the dielectric substrate 60 was changed. Specifically, the thickness (t) of the dielectric base material 60 is changed to 0.2mm (0.027 × λ 0 '), 0.4mm (0.053 × λ 0 '), 0.6mm (0.080 × λ 0 '), 0.8mm (0.11 × λ 0 '), and 1.0mm (0.13 × λ 0 '). λ 0' here is the wavelength in vacuum at 40GHz (≈ 7.5 mm). The conditions of the present simulation are as follows.

[ TABLE 1 ]

Specifically, the matching layer 74 was a Cyclic Olefin Polymer (COP), and the dielectric substrate 60 was a synthetic quartz glass (AQ, trade name, manufactured by AGC Co., Ltd.) and a simulation was performed. In the transmission line region 201B shown in fig. 20B, the XY plane is a square of 10mm × 10 mm. The microstrip line 24 is a straight line having a width of 0.25mm and a length of 3.5mm parallel to the X axis direction, a straight line having a length of 3.5mm parallel to the Y axis, and a straight line having a length of 2.1mm connecting 2 straight lines and forming an angle of 45 ° with respect to the X axis and the Y axis. That is, the microstrip line 24 is a line having 2 bending points bent at 135 ° in the XY plane and having a total length of about 9.1 mm.

Fig. 21 is a graph showing a transmission loss when a signal is transmitted on both ends of the microstrip line 24 in fig. 20B, that is, on a path from a point P1 to a point P2 as a transmission loss (S21: unit [ dB ]) on the microstrip line 24 in the laminated body that becomes the region B. As shown in fig. 21, as the thickness of the dielectric substrate 60 (synthetic quartz glass) becomes thinner, the transmission loss (value of S21) becomes smaller, and the characteristic of S21 with respect to a frequency of 10GHz or more becomes stable (fluctuation is small).

The antenna system has been described above with reference to the embodiments, but the present invention is not limited to the above-described embodiments. Various modifications and improvements such as combination with part or all of the other embodiments, replacement, and the like are possible within the scope of the present invention.

For example, the glass plate is not limited to the vehicle, and may be used for a building or an electronic device.

The international application claims that the entire contents of the two applications are incorporated into the international application based on the priorities of the japanese patent application No. 2018-211375, which is applied on 5/10/2018 and the japanese patent application No. 2018-211308, which is applied on 9/11/2018.

Description of the reference symbols

10. 10a, 10b, 27a, 27b conductor plate

11 center of gravity

20 radiation board (radiation part)

20a gap (radiation part)

21 center of gravity

22 connection point

24. 25 microstrip line

26 strip line

28a, 28b, 28c conductor wall

30 power supply part

40 connecting conductor

51 first engaging member

52 second engaging member

60. 60a, 60b dielectric substrate

70 glass plate

71 front glass

72 rear glass

73 side glass

74 matching layer

75 spacer

76 inside surface

77 outer side surface

80 vehicle

90 horizontal plane

Vertical plane of 91

92 air

100. 101 antenna system

110 antenna

111 front antenna

112 rear antenna

113 array antenna

201. 202, 203, 204, 205 antenna with transmission line

201a antenna area

201b transmission line region