Vehicle Antenna System

Abstract

Provided is a vehicle antenna system in which a MIMO antenna is mounted to a vehicle and whereby it is possible to improve communication capacity. The vehicle antenna system (100) comprises a vehicle (10) and a MIMO antenna (20) that is mounted to the vehicle (10) and transmits / receives radio waves of a predetermined frequency. The MIMO antenna (20) has antennas (21) to (24) including an antenna (21) for transmitting / receiving mainly first polarized waves and an antenna (22) for transmitting / receiving mainly second polarized waves orthogonal to the first polarized waves. The antennas (21) to (24) are arranged on the vehicle (10) in a distributed manner. The antenna (21) and the antenna (22) are arranged on the basis of at least one of (1) a configuration in which one antenna is arranged in a central area and the other antenna is arranged in a first peripheral area or a second peripheral area and (2) a configuration in which one antenna is arranged in a first area and the other antenna is arranged in a second area.

Description

Technical Field

[0001] The present invention relates to a vehicle antenna system.

Background Art

[0002] In recent years, high-speed and high-capacity communication infrastructures using radio waves in frequency bands of 4G LTE (Long Term Evolution) (800 MHz band), 5G (sub6 (~6 GHz)), further millimeter waves (20 GHz to 30 GHz), and millimeter waves (30 GHz to 300 GHz) have been expanding. Along with this, the spread of vehicles equipped with 4G LTE to 5G antennas has also been accelerating.

[0003] Vehicles using 4G LTE to 5G antennas are equipped with antennas capable of transmitting and receiving radio waves of a predetermined frequency at a plurality of locations. Regarding the antennas mounted on such vehicles, MIMO (Multiple Input Multiple Output) antennas are known as a technology for increasing the communication capacity in radio waves of a predetermined frequency band (for example, Patent Document 1 and Patent Document 2). Patent Document 1 discloses a MIMO antenna attached at a location that does not overlap with the sun visor on the windshield. Patent Document 2 discloses that a MIMO antenna is used as an example of an integrated antenna module distributed at a plurality of parts of a vehicle.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] MIMO antennas for vehicle mounting, such as those described in Patent Document 1 and Patent Document 2 above, are desired to be able to communicate a large amount of data, but have not always been sufficient.

[0006] In view of the above problems, an object of the present invention is to provide a vehicle antenna system equipped with a MIMO antenna capable of improving communication capacity.

Means for Solving the Problems

[0007] A vehicle antenna system according to an aspect of the present invention includes a vehicle and a MIMO antenna mounted on the vehicle for transmitting and receiving radio waves of a predetermined frequency. The MIMO antenna has four antennas including a first antenna mainly transmitting and receiving a first polarization wave and a second antenna mainly transmitting and receiving a second polarization wave orthogonal to the first polarization wave. The four antennas are dispersedly arranged on the vehicle. With a center line bisecting the vehicle width as a reference from a perspective in the vertical direction of the vehicle, a region having an equal width at an equal distance in the left and right vehicle width directions is defined as a central region, and two regions sandwiching the central region are defined as a first peripheral region and a second peripheral region. When an arbitrary line extending in the vehicle width direction is used as a boundary to define a front region of the vehicle as a first region and a rear region of the vehicle behind the first region as a second region, the first antenna and the second antenna are arranged based on at least one of (1) a configuration in which one is arranged in the central region and the other is arranged in the first peripheral region or the second peripheral region, and (2) a configuration in which one is arranged in the first region and the other is arranged in the second region.

[0008] In the above vehicle antenna system, the MIMO antenna may include a third antenna mainly transmitting and receiving the first polarization wave and a fourth antenna mainly transmitting and receiving the second polarization wave.

[0009] In the above vehicle antenna system, among the first antenna group including the first antenna and the third antenna, and the second antenna group including the second antenna and the fourth antenna, one may be arranged in the central region and the other may be arranged in at least one of the first peripheral region and the second peripheral region.

[0010] In the above vehicle antenna system, the first antenna and the third antenna are arranged in the central region, the second antenna is arranged in the first peripheral region, and the fourth antenna may be arranged in the second peripheral region, or the first antenna may be arranged in the first peripheral region, the third antenna may be arranged in the second peripheral region, and the second antenna and the fourth antenna may be arranged in the central region.

[0011] In the above vehicle antenna system, the first antenna and the third antenna may be arranged at the same distance from the center line, and the second antenna and the fourth antenna may be arranged at the same distance from the center line.

[0012] In the above vehicle antenna system, the arbitrary line is provided on the roof of the vehicle, and the MIMO antenna may be arranged in the first region or the second region.

[0013] In the above vehicle antenna system, the MIMO antenna may be arranged on the windshield.

[0014] In the above vehicle antenna system, the MIMO antenna may be arranged on the rear glass.

[0015] In the above vehicle antenna system, the arbitrary line is provided on the roof of the vehicle, and among the first antenna group including the first antenna and the third antenna, and the second antenna group including the second antenna and the fourth antenna, one may be arranged in the first region and the other may be arranged in the second region.

[0016] In the above vehicle antenna system, one of the first antenna group and the second antenna group may be disposed on the windshield and the other may be disposed on the rear glass.

[0017] In the above vehicle antenna system, when the predetermined frequency is λ, the wavelength shortening rate of the dielectric for attaching the first antenna and the third antenna is k1, and the wavelength shortening rate of the dielectric for attaching the second antenna and the fourth antenna is k2, the distance between the first antenna and the third antenna may be k1×λ / 2 or more, and the distance between the second antenna and the fourth antenna may be k2×λ / 2 or more.

[0018] In the above vehicle antenna system, the first polarization wave may be a vertical polarization wave, the second polarization wave may be a horizontal polarization wave, the first antenna may be a vertical polarization antenna that mainly transmits and receives a vertical polarization wave, and the second antenna may be a horizontal polarization antenna that mainly transmits and receives a horizontal polarization wave.

[0019] In the above vehicle antenna system, the first polarization wave may be a vertical polarization wave, the second polarization wave may be a horizontal polarization wave, the first antenna and the third antenna may be vertical polarization antennas that mainly transmit and receive a vertical polarization wave, and the second antenna and the fourth antenna may be horizontal polarization antennas that mainly transmit and receive a horizontal polarization wave.

[0020] In the above vehicle antenna system, the width W of the central region C When the width of the vehicle is W, 0.1×W≦W C ≦0.5×W may be satisfied.

[0021] In the above vehicle antenna system, among the MIMO antennas, the antenna disposed in either the first peripheral region or the second peripheral region may be disposed at a distance within 100 mm from the pillar of the vehicle.

[0022] In the above vehicle antenna system, the predetermined frequency may be 3.3 GHz or higher.

[0023] In the above vehicle antenna system, the predetermined frequency may be 6 GHz or lower.

Advantages of the Invention

[0024] According to one aspect of the present invention, it is possible to provide a vehicle antenna system equipped with a MIMO antenna that can improve communication capacity.

Brief Description of the Drawings

[0025]

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[0026] Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments. Also, for the sake of clarity, the following description and drawings have been appropriately omitted and simplified. In each drawing, the same elements are denoted by the same reference numerals, and redundant explanations are omitted as necessary. In addition, in each embodiment, deviations within a range that does not impair the effects of the present invention are allowed in directions such as parallel, horizontal, and vertical. Further, in the drawings for explaining the embodiments, unless otherwise specified, the directions on the drawings shall be referred to.

[0027] (Embodiment) Hereinafter, a configuration example of the vehicle antenna system according to the embodiment will be described. [Example 1] Using FIG. 1, a configuration example of the vehicle antenna system 100 according to Example 1 will be described. FIG. 1 is a figure showing the vehicle of the vehicle antenna system according to Example 1 in a top view. The vehicle antenna system 100 includes a vehicle 10 and a MIMO antenna 20.

[0028] In each drawing, the X-axis direction corresponds to the vehicle width direction of the vehicle 10, the Y-axis direction corresponds to the front-rear direction of the vehicle 10, and the Z-axis direction corresponds to the up-down direction of the vehicle 10. Also, the XY plane corresponds to the horizontal plane, and the Z-axis direction corresponds to the vertical direction perpendicular to the horizontal plane.

[0029] First, before describing the configuration example of the vehicle antenna system 100, terms used in this specification will be explained. In this specification, a virtual region obtained by virtually dividing the region of the vehicle 10 is used. As shown in FIG. 1, from the viewpoint in the vertical direction (positive Z-axis direction) of the vehicle 10, a center line C is provided at a position that bisects the vehicle width, and a region having a width equidistant in the left and right vehicle width directions (X-axis direction) with respect to the center line C is defined as the central region. Specifically, with respect to the center line C, a boundary line B1 is provided at a position separated by a distance Wc1 in the negative X-axis direction of the central region, and a boundary line B2 is provided at a position separated by a distance Wc2, which is the same as the distance Wc1, in the positive X-axis direction of the central region. The region between the boundary line B1 and the boundary line B2 is defined as the central region. The width Wc of the central region may be set so as to satisfy 0.1×W≦Wc≦0.5×W in relation to the vehicle width W of the vehicle 10.

[0030] Next, the two regions sandwiching the central region are defined as the first peripheral region and the second peripheral region. Specifically, the region from the boundary line B1 of the central region to the side surface of the vehicle 10 in the negative X-axis direction is defined as the first peripheral region, and the region from the boundary line B2 of the central region to the side surface of the vehicle 10 in the positive X-axis direction is defined as the second peripheral region. In FIG. 1, the first peripheral region and the second peripheral region may be defined by swapping them, as long as they are arranged so as to sandwich the central region.

[0031] Also, a reference line B3 extending in the vehicle width direction of the vehicle 10 is provided. With the reference line B3 as a boundary, the region in front of the vehicle 10 (positive Y-axis direction) is defined as the front region, and the region behind the front region with respect to the reference line B3 is defined as the rear region. Note that the reference line B3 may be set at an arbitrary position. Also, the front region and the rear region are also referred to as the first region and the second region, respectively.

[0032] The configuration example of the vehicle antenna system 100 will be described below. The vehicle 10 includes a metal body 11, a windshield 12, and a rear glass 13. The vehicle 10 may be any vehicle with an arbitrary shape. Also, the vehicle 10 may include at least one of side glass, front bench glass, rear quarter glass, and roof glass which are fixed windows.

[0033] The MIMO antenna 20 is an antenna mounted on the vehicle 10 for transmitting and receiving radio waves of a predetermined frequency. It is an antenna that uses a plurality of antennas connected to different feeding points to enable multiple input and output at a predetermined frequency. The predetermined frequency may be 3.3 GHz or higher, and in particular, any frequency can be set without an upper limit. Also, the predetermined frequency may be 6 GHz or lower. The MIMO antenna 20 has four antennas, namely antenna 21 to antenna 24, and the antennas 21 to 24 are distributed and arranged on the vehicle 10.

[0034] In Example 1, the reference line B3 is provided on the roof of the metal body 11 of the vehicle 10, and the MIMO antenna 20 is arranged in the front region. The MIMO antenna 20 is an antenna arranged in a dielectric. For example, it is arranged on the inner surface side of the windshield 12. In other words, in Example 1, the antennas 21 to 24 are arranged on the inner surface side of the windshield 12 included in the front region. The antennas 21 to 24 may be directly attached to the windshield 12 so as to physically contact it. Or the antennas 21 to 24 may be indirectly attached to the windshield 12 via, for example, a housing or the like.

[0035] Incidentally, the MIMO antenna 20 may be disposed in the rear area. In that case, the MIMO antenna 20 may be disposed on the inner surface side of the rear glass 13, may be disposed on the inner surface side of the side glass, or may be disposed inside an aerodynamic part such as a rear spoiler. Also, the shape of each of the antennas 21 to 24 may be arbitrary, such as a patch antenna, a slot antenna, a dipole antenna, etc. In this specification, the antenna 21, the antenna 22, the antenna 23, and the antenna 24 are also referred to as the first antenna, the second antenna, the fourth antenna, and the third antenna, respectively.

[0036] The antenna 21 is an antenna that mainly transmits and receives the first polarization wave. An antenna that mainly transmits and receives the first polarization wave is an antenna in which the antenna gain of the first polarization wave is higher than the antenna gain of the second polarization wave orthogonal to the first polarization wave. In other words, an antenna that mainly transmits and receives the first polarization wave is an antenna in which the channel capacity in the first polarization wave is larger than the channel capacity in the second polarization wave. For an antenna that mainly transmits and receives the first polarization wave, when the antenna gain of the first polarization wave at a predetermined frequency is G1 [dBi] and the antenna gain of the second polarization wave is G2 [dBi], G1 - G2 may be 10 [dB] or more, and preferably 15 [dB] or more. The first polarization wave may be a vertical polarization wave, a horizontal polarization wave, or a circular polarization wave. When the first polarization wave is a vertical polarization wave, the second polarization wave is a horizontal polarization wave, and when the first polarization wave is a horizontal polarization wave, the second polarization wave is a vertical polarization wave. Further, when the first polarization wave is a first circular polarization wave, the second polarization wave is a second circular polarization wave orthogonal to the first circular polarization wave. The first circular polarization wave and the second circular polarization wave may be either a combination of a left polarization wave and a right polarization wave or a combination of a right polarization wave and a left polarization wave.

[0037] The antenna 21 is disposed, for example, in the first peripheral area. The antenna 21 is disposed, for example, in proximity to a pillar 11wa (A-pillar 11wa) included in the metal body 11 of the vehicle 10. Note that "disposed in proximity to the pillar 11wa" means disposed in proximity to such an extent that the antenna 21 does not contact the pillar. In other words, the antenna 21 is disposed in proximity to an edge 11wb in the negative X-axis direction of the windshield 12.

[0038] Antenna 22 is an antenna that mainly transmits and receives the second polarization wave. An antenna that mainly transmits and receives the second polarization wave is an antenna in which the antenna gain of the second polarization wave is higher than the antenna gain of the first polarization wave. For an antenna that mainly transmits and receives the second polarization wave, at a predetermined frequency, it is sufficient that G2 - G1, which is the difference between the antenna gain of the second polarization wave and the antenna gain of the first polarization wave, is 10 [dB] or more, and preferably 15 [dB] or more.

[0039] Antenna 22 is arranged, for example, in the central region. In addition, in Example 1, antenna 22 may be arranged in the first peripheral region and antenna 21 may be arranged in the central region. That is, in Example 1, one of antenna 21 and antenna 22 is arranged in the central region, and the other is arranged in the first peripheral region or the second peripheral region.

[0040] In this example, antenna 23 and antenna 24 may each be an antenna that mainly transmits and receives the first polarization wave, or may be an antenna that mainly transmits and receives the second polarization wave. Furthermore, both antenna 23 and antenna 24 may be antennas that transmit and receive the antenna gains of the first polarization wave and the second polarization wave at the same level and have no bias in the channel capacity due to polarization. Also, antenna 23 and antenna 24 may each be dispersedly arranged in any of the central region, the first peripheral region, and the second peripheral region. In an example shown in FIG. 1, antenna 23 and antenna 24 are arranged in the central region.

[0041] Next, with reference to FIG. 2, an arrangement example of antenna 21 arranged in the first peripheral region will be described. FIG. 2 is an enlarged view showing the windshield in a plan view and enlarging the first peripheral region. As shown in FIG. 2, antenna 21 includes, for example, a power feeding unit 21a, an antenna element 21b, and an antenna element 21c. Note that antennas 22 to 24 also include a power feeding unit and two antenna elements, similar to antenna 21. In the following description, illustration of the power feeding units and antenna elements of antennas 21 to 24 will be omitted.

[0042] The antenna 21 is arranged in the first peripheral area and is arranged close to the pillar 11wa adjacent to the edge 11wb in the negative X-axis direction of the windshield 12 among the metal bodies 11. The antenna 21 is arranged at a distance within Dw1 from the pillar 11wa. In other words, the distance Dw1 may be 100 [mm] or 50 [mm]. The same applies to the antenna arranged in the second peripheral area. That is, the antenna arranged in the second peripheral area may be arranged within 100 [mm] or 50 [mm] while being away from the pillar of the vehicle 10. Also, the distance between the antenna arranged in the second peripheral area and the pillar of the vehicle 10 may be the same as or different from the distance Dw1.

[0043] As described above, the antennas 21 to 24 included in the MIMO antenna 20 are arranged dispersedly on the vehicle 10. Also, among the antenna 21 and the antenna 22, one is an antenna that mainly transmits and receives the first polarization wave, and the other is an antenna that mainly transmits and receives the second polarization wave. Further, among the antenna 21 and the antenna 22, one is arranged in the central area, and the other is arranged in the first peripheral area or the second peripheral area. The vehicle antenna system 100 includes the antenna 21 and the antenna 22 whose polarization waves are orthogonal to each other and are arranged in different areas, so that even when the communication capacity in one polarization wave signal is low, it can be complemented by the communication capacity in the other polarization wave signal, thus ensuring the stability of communication. Therefore, since the antenna 21 and the antenna 22 of the vehicle antenna system 100 function as antennas that ensure the stability of communication, the communication capacity can be improved.

[0044] [Example 2] Next, with reference to FIG. 3, a configuration example of the vehicle antenna system 110 according to Example 2 will be described. FIG. 3 is a top view of the vehicle of the vehicle antenna system according to Example 2. In Example 2, one of the antennas 21 and 22 is arranged in the front region, and the other is arranged in the rear region. The position where the antenna 22 included in the MIMO antenna 20 according to Example 1 is arranged in the vehicle antenna system 110 is different. Since the configuration examples of the vehicle 10 and the antennas 21 to 24 are the same as those in Example 1, descriptions common to the vehicle antenna system 100 according to Example 1 will be omitted as appropriate.

[0045] As shown in FIG. 3, in Example 2, the reference line B3 is provided on the roof of the vehicle 10 as in Example 1, but is provided at a position in the negative Y-axis direction compared to Example 1. The antennas 21, 23, and 24 are arranged on the inner surface side of the windshield 12 included in the front region. The antenna 22 is arranged in the rear region, for example, on the inner surface side of the rear glass 13. The antenna 22 is arranged, for example, in the first peripheral region. The antenna 22 is arranged, for example, in the vicinity of the pillar 11ra included in the metal body 11 of the vehicle 10 and is spaced apart at a distance within Dr1 from the pillar 11ra. In other words, the antenna 22 is arranged in the vicinity of the edge 11rb in the negative X-axis direction of the rear glass 13 and is spaced apart at a distance within Dr1 from the edge 11rb. The distance Dr1 may be 100 [mm] or 50 [mm]. The distance Dr1 may be the same value as the distance Dw1 or a different value.

[0046] Note that since the reference line B3 can be set at an arbitrary position, the reference line B3 in Example 2 may be provided at the same position as the reference line B3 in Example 1. In Example 2, since one of the antennas 21 and 22 is arranged in the front region and the other is arranged in the rear region, the antenna 21 may be arranged in the rear region and the antenna 22 may be arranged in the front region. Also, since one of the antennas 21 and 22 only needs to be arranged in the front region, for example, it may be arranged inside an aerodynamic part (shark fin) provided near the center line C of the rear part on the roof of the vehicle 10. In FIG. 2, the antennas 21 and 22 are arranged in the first peripheral region, but may be arranged in a combination of the central region and the second peripheral region, respectively.

[0047] Regarding Example 2 as well, similar to Example 1, the antennas 21 to 24 included in the MIMO antenna 20 are distributed and arranged on the vehicle 10. Also, one of the antennas 21 and 22 is an antenna that mainly transmits and receives the first polarization wave, and the other is an antenna that mainly transmits and receives the second polarization wave. Further, one of the antennas 21 and 22 is arranged in the front region and the other is arranged in the rear region. The vehicle antenna system 110 includes the antennas 21 and 22 whose polarization waves are orthogonal to each other and are arranged in different regions, so that even when the communication capacity in one polarization wave signal is low, it can be complemented by the communication capacity in the other polarization wave signal, thus ensuring the stability of communication. Therefore, similar to the vehicle antenna system 100 according to Example 1, the vehicle antenna system 110 can improve the communication capacity because the antennas 21 and 22 function as antennas that ensure the stability of communication.

[0048] Although Example 1 and Example 2 have been described as separate configurations, at least one of the vehicle antenna system 100 and the vehicle antenna system 110 may have a configuration combining Example 1 and Example 2. That is, Example 1, Example 2, or a combination of Example 1 and Example 2 is possible. Therefore, the antennas 21 and 22 may be arranged based on at least one of (1) a configuration in which one is arranged in the central region and the other is arranged in the first peripheral region or the second peripheral region, and (2) a configuration in which one is arranged in the first region and the other is arranged in the second region.

[0049] Hereinafter, specific examples of Example 1 and Example 2 will be described. [Example 3] Using FIG. 4, a configuration example of the vehicle antenna system 120 according to Example 3 will be described. FIG. 4 is a view showing the vehicle of the vehicle antenna system according to Example 3 from above. The vehicle antenna system 120 includes a vehicle 10 and a MIMO antenna 30. Example 3 is a specific example of Example 1, and has a configuration in which the MIMO antenna 30 is arranged in the front region. Note that in the following examples including Example 3, similar to Example 1, the reference line B3 is provided on the roof of the metal body 11 of the vehicle 10, but the reference line B3 may be provided at the same position as in Example 2.

[0050] The MIMO antenna 30 is an antenna mounted on the vehicle 10 for transmitting and receiving radio waves of a predetermined frequency, and is an antenna capable of multiple input and output at a predetermined frequency using a plurality of antennas connected to different feeding points. The predetermined frequency may be 3.3 GHz or higher, and in particular, any frequency can be set without an upper limit. Also, the predetermined frequency may be 6 GHz or lower. The MIMO antenna 30 in this example is arranged on the windshield 12.

[0051] The MIMO antenna 30 has four antennas, namely antennas 31 to 34, and antennas 31 to 34 are distributed and arranged on the vehicle 10. Antennas 31 to 34 are arranged on the inner surface side of the windshield 12. Antennas 31 to 34 may be directly attached to the windshield 12 so as to be physically in contact therewith. Alternatively, antennas 31 to 34 may be indirectly attached to the inner surface side of the windshield 12 via, for example, a housing or the like. Antennas 31 to 34 are arranged at positions that do not obstruct the view of the occupants of the vehicle 10, and are arranged, for example, in the vicinity of the upper edge portion 11we of the windshield 12. The shape of each of antennas 31 to 34 may be arbitrary as long as it can transmit and receive radio waves of a predetermined frequency. The same applies to the following examples including Example 3. Antennas 31, 32, 33, and 34 are also referred to as the first antenna, the second antenna, the fourth antenna, and the third antenna, respectively.

[0052] Antenna 31 corresponds to antenna 21 in Examples 1 and 2. Antenna 31 is a vertical polarization antenna that mainly transmits and receives vertically polarized waves. Note that antenna 31 may also be a horizontal polarization antenna that mainly transmits and receives horizontally polarized waves, or a circular polarization antenna that mainly transmits and receives circularly polarized waves. The circular polarization may be left-handed circular polarization or right-handed circular polarization.

[0053] Antenna 31 is arranged on the inner surface side of the windshield 12 included in the front region and is arranged in the first peripheral region. Antenna 31 is arranged in the vicinity of the pillar 11wa included in the metal body 11 of the vehicle 10. In other words, antenna 31 is arranged in the vicinity of the edge portion 11wb in the negative X-axis direction of the windshield 12.

[0054] Antenna 32 corresponds to antenna 22 in Example 1 and Example 2. Antenna 32 is a horizontal polarization antenna that mainly transmits and receives a horizontal polarization wave that is orthogonal to the polarization wave mainly transmitted and received by antenna 31. Note that the polarization wave mainly transmitted and received by antenna 32 is not limited to the horizontal polarization wave, and any polarization wave orthogonal to the polarization wave mainly transmitted and received by antenna 31 is acceptable. Antenna 32 is disposed on the vehicle interior surface side of the windshield 12 included in the front region and is disposed in the central region.

[0055] Antenna 33 is a horizontal polarization antenna that mainly transmits and receives a horizontal polarization wave that is the same as the polarization wave mainly transmitted and received by antenna 32. The polarization wave mainly transmitted and received by antenna 33 may be the same as the polarization wave mainly transmitted and received by antenna 32. Antenna 33 is disposed on the vehicle interior surface side of the windshield 12 included in the front region and is disposed in the central region.

[0056] Antenna 34 is a vertical polarization antenna that mainly transmits and receives a vertical polarization wave that is the same as the polarization wave mainly transmitted and received by antenna 32. The polarization wave mainly transmitted and received by antenna 34 may be the same as the polarization wave mainly transmitted and received by antenna 31. Antenna 34 is disposed on the vehicle interior surface side of the windshield 12 included in the front region and is disposed in the second peripheral region. Antenna 34 is disposed in proximity to a pillar 11wc (A-pillar 11wc) included in the metal body 11 of the vehicle 10. Note that "disposed in proximity to the pillar 11wc" means that antenna 34 is disposed in proximity to the extent that it does not contact the pillar. In other words, antenna 34 is disposed in proximity to an edge 11wd on the positive X-axis side among the edges located in the vehicle width direction of the windshield 12.

[0057] Note that the antenna 34 may be disposed in the first peripheral region. That is, the antenna 31 and the antenna 34 may be disposed in at least one of the first peripheral region and the second peripheral region, and the antenna 32 and the antenna 33 may be disposed in the central region. Alternatively, the antenna 32 and the antenna 33 may be disposed in at least one of the first peripheral region and the second peripheral region, and the antenna 31 and the antenna 34 may be disposed in the central region. Here, the antenna 31, which is the first antenna, and the antenna 34, which is the third antenna, are defined as the first antenna group, and the antenna 32, which is the second antenna, and the antenna 33, which is the fourth antenna, are defined as the second antenna group. In this case, one of the first antenna group and the second antenna group may be disposed in the central region, and the other may be disposed in at least one of the first peripheral region and the second peripheral region.

[0058] Next, with reference to FIG. 5, an example of the arrangement of the antennas 31 to 34 on the windshield 12 will be described. FIG. 5 is a diagram showing the windshield in a plan view. The antenna 31 is disposed in the first peripheral region and is spaced apart at a distance within Dw1 from the pillar 11wa of the vehicle 10. The distance Dw1 may be 100 [mm] or 50 [mm]. The antenna 31 is disposed at a position of a distance DC13 from the center line C. The antenna 32 is disposed in the central region and is disposed at a position of a distance DC24 from the center line C.

[0059] Antenna 33 is disposed in the central region and is disposed at a position at a distance DC24 from the center line C. In other words, antenna 32, which is the second antenna, and antenna 33, which is the fourth antenna, are disposed at the same distance from the center line C. Note that since antenna 32 and antenna 33 only need to be disposed in the central region, they do not necessarily have to be disposed at the same distance from the center line C. Further, antenna 33 is disposed at a position at a distance D24 from antenna 32. The distance D24 may be set to be k1×λ / 2 or more, where λ is the wavelength of the radio wave in the air at the frequency at which MIMO antenna 30 transmits and receives, and k1 is the wavelength shortening rate of the dielectric to which antenna 32 and antenna 33 are attached. If the distance D24, which is twice the distance DC24, is set to be k1×λ / 2 or more, antenna correlation can be suppressed, that is, interference between the same polarization waves in antenna 32 and antenna 33 can be suppressed, so that the antenna gain and communication capacity can be improved.

[0060] The antenna 34 is disposed in the second peripheral region and spaced apart from the pillar 11wc of the vehicle 10 at a distance within Dw2. The distance Dw2 may be 100 [mm] or 50 [mm]. Note that the distance Dw2 may be the same as or different from the distance Dw1. The antenna 34 is disposed at a position of a distance DC13 from the center line C. In Example 3, the antenna 31 which is the first antenna and the antenna 34 which is the third antenna are disposed at the same distance from the center line C. Note that since either one of the antenna 31 and the antenna 34 may be disposed in the first peripheral region and the other may be disposed in the second peripheral region, the antenna 31 and the antenna 34 do not have to be disposed at the same distance from the center line C. The antenna 34 is disposed at a position of a distance D13 from the antenna 31. When the wavelength of the radio wave in the air of the frequency at which the MIMO antenna 30 transmits and receives is λ and the wavelength shortening rate of the dielectric in which the antenna 31 and the antenna 34 are mounted is k2, if D13 is k2×λ / 2 or more, antenna correlation can be suppressed, that is, interference between the same polarizations in the antenna 31 and the antenna 34 can be suppressed, so that the antenna gain and the communication capacity can be improved. Note that in Example 3, since the antennas 31 to 34 are mounted on the windshield 12 which is the same dielectric, k1 and k2 have the same value, so the distance D13 and the distance D24 may be k1×λ / 2 or more. Further, the distance between adjacent antennas (for example, the distance between the antenna 31 and the antenna 32) may be k1×λ / 2 or more.

[0061] Next, the communication capacity of the vehicle antenna system 120 will be described. In order to evaluate the communication capacity of the vehicle antenna system 120, the communication capacity of the vehicle antenna system 120 is used with respect to the communication capacity of a configuration in which all the antennas of the vehicle antenna system 120 are replaced with vertical polarization antennas. Further, in order to evaluate the communication capacity of the vehicle antenna system 120, the communication capacity of the vehicle antenna system 120 is used with respect to the communication capacity of a configuration in which all the antennas of the vehicle antenna system 120 are replaced with horizontal polarization antennas.

[0062] In the following description, a configuration in which all the antennas of the vehicle antenna system are replaced with vertical polarization antennas is referred to as "default configuration 1", and a configuration in which all the antennas of the vehicle antenna system are replaced with horizontal polarization antennas is referred to as "default configuration 2". In other words, in default configuration 1, the arrangement of each antenna included in the vehicle antenna system is the same as that of the vehicle antenna system, but antennas 32 and 33 are replaced with vertical polarization antennas. Further, in default configuration 2, the arrangement of each antenna included in the vehicle antenna system is the same as that of the vehicle antenna system, but antennas 31 and 34 are replaced with horizontal polarization antennas.

[0063] The following settings were made for the vehicle antenna system 120, default configuration 1, and default configuration 2. (Center) frequency transmitted and received by the MIMO antenna 30: 3.7 [GHz] Bandwidth of the frequency transmitted and received by the MIMO antenna 30: 100 [MHz] Vehicle width W: 1710 [mm] Distance D24: 345 [mm] Distance D13: 1530 [mm]

[0064] The vehicle 10 of the vehicle antenna system 120, default configuration 1, and default configuration 2 was driven the same distance in simulation on a path with no line of sight to the base station and a path with a line of sight to the base station, and the respective communication capacities (unit: [bit / s / Hz]) were calculated. Then, the communication capacity of the vehicle antenna system 120 was calculated as a relative value when the communication capacities of default configuration 1 and default configuration 2 were set to 100%. As a result of calculating the communication capacity, the communication capacity of the vehicle antenna system 120 with respect to default configuration 1 was 117%. Also, the communication capacity of the vehicle antenna system 120 with respect to default configuration 2 was 124%.

[0065] As described above, in the vehicle antenna system 120, antennas 31 to 34 included in the MIMO antenna 30 are configured as vertical polarization antennas or horizontal polarization antennas and are distributed and arranged on the vehicle 10. The vehicle antenna system 120 according to Example 3 can improve the communication capacity as compared with the case where all the antennas are configured as vertical polarization antennas as in the default configuration 1. Further, the vehicle antenna system 120 according to Example 3 can improve the communication capacity as compared with the case where all the antennas are configured as horizontal polarization antennas as in the default configuration 2.

[0066] [Example 4] Subsequently, with reference to FIG. 6, a configuration example of the vehicle antenna system 130 according to Example 4 will be described. FIG. 6 is a top view of the vehicle of the vehicle antenna system according to Example 4. The vehicle antenna system 130 includes a vehicle 10 and a MIMO antenna 30, as in Example 3. Example 4 is a specific example of Example 1, and similar to Example 3, the MIMO antenna 30 is configured to be disposed in the front region. In the following examples as well, since the vehicle antenna system includes the vehicle 10 and the MIMO antenna 30, descriptions common to Example 3 will be omitted as appropriate.

[0067] In Example 4, the positions where the antennas 31 and 34, which are vertical polarization antennas in Example 3, are disposed and the positions where the antennas 32 and 33, which are horizontal polarization antennas, are disposed are interchanged. Note that in the following examples including Example 4, the configuration examples of the antennas 31 to 34 are basically the same as those in Example 3, although the disposed positions are different from those in other examples. Therefore, in the following description, descriptions common to Example 3 will be omitted as appropriate.

[0068] Antenna 31 is disposed at the position of antenna 32 according to Example 3. Antenna 31 is disposed on the vehicle interior surface side of the windshield 12 included in the front region and is disposed in the central region. Antenna 32 is disposed at the position of antenna 31 according to Example 3. Antenna 32 is disposed on the vehicle interior surface side of the windshield 12 included in the front region and is disposed in the first peripheral region. Antenna 32 is disposed in proximity to the pillar 11wa included in the metal body 11 of the vehicle 10.

[0069] Antenna 33 is disposed at the position of antenna 34 according to Example 3. Antenna 33 is disposed on the vehicle interior surface side of the windshield 12 included in the front region and is disposed in the second peripheral region. Antenna 33 is disposed in proximity to the pillar 11wc included in the metal body 11 of the vehicle 10. Antenna 34 is disposed at the position of antenna 33 according to Example 3. Antenna 34 is disposed on the vehicle interior surface side of the windshield 12 included in the front region and is disposed in the central region.

[0070] Although not shown, in Example 4 as well, antenna 31 which is the first antenna and antenna 34 which is the third antenna are disposed at the same distance from the center line C, and antenna 32 which is the second antenna and antenna 33 which is the fourth antenna are disposed at the same distance from the center line C. Note that antenna 31 and antenna 34 do not necessarily have to be disposed at the same distance from the center line C, and antenna 32 and antenna 33 do not necessarily have to be disposed at the same distance from the center line C. Also, the distance D24 between antenna 32 and antenna 33 and the distance D13 between antenna 31 and antenna 34 may be set to be k1×λ / 2 or more in order to suppress antenna correlation and improve antenna gain and communication capacity, and the distance between adjacent antennas may also be set to be k1×λ / 2 or more.

[0071] Next, the communication capacity of the vehicle antenna system 130 will be described. Since the evaluation method is the same as that in Example 3, the description thereof will be omitted. The following settings were made for the vehicle antenna system 130, the default configuration 1, and the default configuration 2. Note that since the frequency at which the MIMO antenna 30 transmits and receives, the bandwidth of the frequency, and the vehicle width W are the same in and after Example 5, the description thereof will be omitted in the following explanation. (Center) frequency at which the MIMO antenna 30 transmits and receives: 3.7 [GHz] Bandwidth of the frequency at which the MIMO antenna 30 transmits and receives: 100 [MHz] Vehicle width W: 1710 [mm] Distance D24: 1530 [mm] Distance D13: 345 [mm]

[0072] As a result of calculating the communication capacity, the communication capacity of the vehicle antenna system 130 with respect to the default configuration 1 was 124 [%]. Further, the communication capacity of the vehicle antenna system 130 with respect to the default configuration 2 was 131 [%].

[0073] As described above, the vehicle antenna system 130 has a configuration different from that of the vehicle antenna system 120 according to Example 3 in the arrangement of the antennas 31 to 34. As described above, the vehicle antenna system 130 according to Example 4 can improve the communication capacity as compared with the default configuration 1 and the default configuration 2.

[0074] [Example 5] Subsequently, with reference to FIG. 7, a configuration example of the vehicle antenna system 140 according to Example 5 will be described. FIG. 7 is a view showing the vehicle of the vehicle antenna system according to Example 5 from above. Example 5 is a specific example of Example 1 and has a configuration in which the MIMO antenna 30 is arranged in the rear region.

[0075] Antennas 31 to 34 are arranged on the rear glass 13 included in the rear region. Antenna 31 is arranged on the rear glass 13 included in the rear region and is also arranged in the first peripheral region. Antenna 31 is arranged close to the pillar 11ra (C-pillar 11ra) included in the metal body 11 of the vehicle 10. In other words, Antenna 31 is arranged close to the edge 11rb in the negative X-axis direction of the rear glass 13. Note that "arranged close to the pillar 11ra" means an arrangement close enough that the conductor of Antenna 31 does not contact the pillar. Also, Antenna 31 is arranged, for example, close to the lower edge 11rf of the rear glass 13.

[0076] Antennas 32 and 33 are arranged on the inner surface side of the rear glass 13 included in the rear region and are also arranged in the central region. Antennas 32 and 33 are arranged, for example, close to the upper edge 11re of the rear glass 13.

[0077] Antenna 34 is arranged on the inner surface side of the rear glass 13 included in the rear region and is also arranged in the second peripheral region. Antenna 34 is arranged close to the pillar 11rc (C-pillar 11rc) included in the metal body 11 of the vehicle 10. In other words, Antenna 34 is arranged close to the edge 11rd on the positive X-axis side among the edges located in the vehicle width direction of the rear glass 13. Note that "arranged close to the pillar 11rc" means an arrangement close enough that the conductor of Antenna 34 does not contact the pillar. Also, Antenna 34 is arranged, for example, close to the lower edge 11rf of the rear glass 13.

[0078] Note that the antenna 34 may be disposed in the first peripheral region. That is, the antenna 31 and the antenna 34 may be disposed in at least one of the first peripheral region and the second peripheral region, and the antenna 32 and the antenna 33 may be disposed in the central region. Alternatively, the antenna 32 and the antenna 33 may be disposed in at least one of the first peripheral region and the second peripheral region, and the antenna 31 and the antenna 34 may be disposed in the central region. In other words, of the first antenna group including the antenna 31 and the antenna 34 and the second antenna group including the antenna 32 and the antenna 33, one may be disposed in the central region and the other may be disposed in at least one of the first peripheral region and the second peripheral region.

[0079] Next, with reference to FIG. 8, an example of the arrangement of the antennas 31 to 34 in the rear glass 13 will be described. FIG. 8 is a diagram showing the rear glass in a plan view. The antenna 31 is disposed close to the lower edge portion 11rf of the rear glass 13. The antenna 31 is disposed in the first peripheral region and is spaced apart at a distance within a distance Dr1 from the pillar 11ra of the vehicle 10. The distance Dr1 may be 100 [mm] or may be 50 [mm]. Note that the distance Dr1 may be the same value as at least one of the distances Dw1 and Dw2, or may be a value different from the distances Dw1 and Dw2. The antenna 31 is disposed at a position of a distance DC13 from the center line C.

[0080] The antenna 32 is disposed close to the upper edge portion 11re of the rear glass 13. The antenna 32 is disposed in the central region and is disposed at a position of a distance DC24 from the center line C.

[0081] The antenna 33 is disposed close to the upper edge portion 11re of the rear glass 13. The antenna 33 is disposed in the central region and is disposed at a position of a distance D24 which is the same distance as the distance from the center line C to the antenna 32 from the center line C. Note that the distance between the antenna 33 and the center line C may be different from the distance between the antenna 32 and the center line C. Also, the antenna 33 is disposed at a position of a distance D24 from the antenna 32. The distance D24 may be k1×λ / 2 or more as in Example 3.

[0082] Antenna 34 is disposed close to the lower edge portion 11rf of the rear glass 13. Antenna 34 is disposed in the second peripheral region and is spaced apart at a distance within a distance Dr2 from the pillar 11rc of the vehicle 10. The distance Dr2 may be 100 [mm] or may be 50 [mm]. Note that the distance Dr2 may be the same value as at least one of the distance Dr1, the distance Dw1, and the distance Dw2, or may be a value different from the distance Dr1, the distance Dw1, and the distance Dw2. Antenna 34 is disposed at a position of a distance DC13 that is the same distance from the center line C as the distance from the center line C to antenna 31. Note that the distance between antenna 34 and the center line C may be different from the distance between antenna 31 and the center line C. Antenna 34 is disposed at a position of a distance D13 from antenna 31. The distance D24 may be k2×λ / 2 or more, similar to Example 3. Note that also in Example 5, since antennas 31 to 34 are attached to the rear glass 13 which is the same dielectric, k1 and k2 have the same value.

[0083] Next, the communication capacity of the vehicle antenna system 140 will be described. Since the evaluation method is the same as in Example 3, the description thereof will be omitted. The following settings were made for the vehicle antenna system 140, the default configuration 1, and the default configuration 2. Distance D24: 700 [mm] Distance D13: 1470 [mm]

[0084] As a result of calculating the communication capacity, the communication capacity of the vehicle antenna system 140 with respect to the default configuration 1 was 122 [%]. Also, the communication capacity of the vehicle antenna system 140 with respect to the default configuration 2 was 117 [%].

[0085] As described above, even when the MIMO antenna 30 is disposed on the rear glass 13 included in the rear region, the vehicle antenna system 140 according to Example 5 can improve the communication capacity as compared with the default configuration 1 and the default configuration 2.

[0086] [Example 6] Next, with reference to FIG. 9, a configuration example of the vehicle antenna system 150 according to Example 6 will be described. FIG. 9 is a top view of the vehicle of the vehicle antenna system according to Example 6. Example 6 is a specific example of Example 1. Example 6 has a configuration in which the positions where the antennas 31 and 32, which are vertical polarization antennas, are arranged and the positions where the antennas 32 and 33, which are horizontal polarization antennas, are arranged in Example 5 are interchanged.

[0087] Antenna 31 is arranged at the position of antenna 32 according to Example 5. Antenna 31 is arranged on the inner surface side of the rear glass 13 included in the rear region and in the central region. Antenna 31 is arranged close to the upper edge portion 11re of the rear glass 13.

[0088] Antenna 32 is arranged at the position of antenna 31 according to Example 5. Antenna 32 is arranged on the inner surface side of the rear glass 13 included in the rear region and in the first peripheral region. Antenna 32 is arranged close to the pillar 11ra included in the metal body 11 of the vehicle 10. Also, antenna 32 is arranged close to the lower edge portion 11rf of the rear glass 13.

[0089] Antenna 33 is arranged at the position of antenna 34 according to Example 5. Antenna 33 is arranged on the inner surface side of the rear glass 13 included in the rear region and in the second peripheral region. Antenna 33 is arranged close to the pillar 11rc included in the metal body 11 of the vehicle 10. Also, antenna 33 is arranged close to the lower edge portion 11rf of the rear glass 13.

[0090] Antenna 34 is arranged at the position of antenna 33 according to Example 5. Antenna 34 is arranged on the inner surface side of the rear glass 13 included in the rear region and in the central region. Antenna 34 is arranged close to the upper edge portion 11re of the rear glass 13.

[0091] Although illustration is omitted, in the examples after Example 6 including Example 6, the antenna 31 which is the first antenna and the antenna 34 which is the third antenna may be arranged at the same distance from the center line C. Also, the antenna 32 which is the second antenna and the antenna 33 which is the fourth antenna may be arranged at the same distance from the center line C. Further, the distance D24 between the antenna 32 and the antenna 33 and the distance D13 between the antenna 31 and the antenna 34 may be set to k1×λ / 2 or more in order to suppress antenna correlation and improve antenna gain and communication capacity, and the distance between adjacent antennas may also be set to k1×λ / 2 or more.

[0092] Next, the communication capacity of the vehicle antenna system 150 will be described. Since the evaluation method is the same as that in Example 3, the description thereof will be omitted. The following settings were made for the vehicle antenna system 150, the default configuration 1, and the default configuration 2. Distance D24: 1470 [mm] Distance D13: 700 [mm]

[0093] As a result of calculating the communication capacity, the communication capacity of the vehicle antenna system 150 with respect to the default configuration 1 was 124 [%]. Also, the communication capacity of the vehicle antenna system 150 with respect to the default configuration 2 was 119 [%].

[0094] As described above, the vehicle antenna system 150 according to Example 6 can improve the communication capacity as compared with the default configuration 1 and the default configuration 2.

[0095] [Example 7] Next, with reference to FIG. 10, a configuration example of the vehicle antenna system 160 according to Example 7 will be described. FIG. 10 is a top view of the vehicle of the vehicle antenna system according to Example 7. Example 7 is a specific example of Example 2. In Example 7, the antennas 31 and 34 are arranged at the same positions as in Example 3, and the antennas 32 and 33 are arranged at the same positions as in Example 6. In Example 7, a first antenna group including the antenna 31 as the first antenna and the antenna 34 as the third antenna is arranged in the front region, and a second antenna group including the antenna 32 as the second antenna and the antenna 33 as the fourth antenna is arranged in the rear region. Further, in Example 7, the first antenna group is arranged on the windshield, and the second antenna group is arranged on the rear glass.

[0096] The antenna 31 is arranged at the same position as the antenna 31 according to Example 3. The antenna 31 is arranged on the inner surface side of the windshield 12 included in the front region and in the first peripheral region. The antenna 31 is arranged close to the pillar 11wa of the vehicle 10. Also, the antenna 31 is arranged close to the upper edge portion 11we of the windshield 12.

[0097] The antenna 32 is arranged at the same position as the antenna 32 according to Example 6. The antenna 32 is arranged on the inner surface side of the rear glass 13 included in the rear region and in the first peripheral region. The antenna 32 is arranged close to the pillar 11ra of the vehicle 10. Also, the antenna 32 is arranged close to the lower edge portion 11rf of the rear glass 13.

[0098] The antenna 33 is arranged at the same position as the antenna 33 according to Example 6. The antenna 33 is arranged on the inner surface side of the rear glass 13 included in the rear region and in the second peripheral region. The antenna 33 is arranged close to the pillar 11rc of the vehicle 10. Also, the antenna 33 is arranged close to the lower edge portion 11rf of the rear glass 13.

[0099] The antenna 34 is arranged at the same position as the antenna 34 according to Example 3. The antenna 34 is arranged on the vehicle interior surface side of the windshield 12 included in the front region and is arranged in the second peripheral region. The antenna 34 is arranged close to the pillar 11wc of the vehicle 10. Also, the antenna 34 is arranged close to the upper edge portion 11we of the windshield 12.

[0100] Next, the communication capacity of the vehicle antenna system 160 will be described. Since the evaluation method is the same as that in Example 3, the description will be omitted. The following settings were made for the vehicle antenna system 160, the default configuration 1, and the default configuration 2. Distance D24: 1530 [mm] Distance D13: 1470 [mm]

[0101] As a result of calculating the communication capacity, the communication capacity of the vehicle antenna system 160 with respect to the default configuration 1 was 113 [%]. Also, the communication capacity of the vehicle antenna system 160 with respect to the default configuration 2 was 124 [%].

[0102] As described above, the vehicle antenna system 160 according to Example 7 can improve the communication capacity as compared with the default configuration 1 and the default configuration 2.

[0103] [Example 8] Next, with reference to FIG. 11, a configuration example of the vehicle antenna system 170 according to Example 8 will be described. FIG. 11 is a view showing the vehicle of the vehicle antenna system according to Example 8 from above. Example 8 is a specific example of Example 2. In Example 8, the positions where the antennas 31 and 34, which are vertical polarization antennas in Example 7, are arranged and the positions where the antennas 32 and 33, which are horizontal polarization antennas, are arranged are interchanged. In Example 8, a first antenna group including the antenna 31 as the first antenna and the antenna 34 as the third antenna is arranged in the rear region, and a second antenna group including the antenna 32 as the second antenna and the antenna 33 as the fourth antenna is arranged in the front region. Further, in Example 8, the first antenna group is arranged on the rear windshield, and the second antenna group is arranged on the windshield.

[0104] The antenna 31 is arranged at the same position as the antenna 32 according to Example 7. The antenna 31 is arranged on the inner surface side of the rear windshield 13 included in the rear region and in the first peripheral region. The antenna 31 is arranged close to the pillar 11ra of the vehicle 10. Also, the antenna 31 is arranged close to the lower edge portion 11rf of the rear windshield 13.

[0105] The antenna 32 is arranged at the same position as the antenna 31 according to Example 7. The antenna 32 is arranged on the inner surface side of the windshield 12 included in the front region and in the first peripheral region. The antenna 32 is arranged close to the pillar 11wa of the vehicle 10. Also, the antenna 32 is arranged close to the upper edge portion 11we of the windshield 12.

[0106] The antenna 33 is arranged at the same position as the antenna 34 according to Example 7. The antenna 33 is arranged on the inner surface side of the windshield 12 included in the front region and in the second peripheral region. The antenna 33 is arranged close to the pillar 11wc of the vehicle 10. Also, the antenna 33 is arranged close to the upper edge portion 11we of the windshield 12.

[0107] Antenna 34 is disposed at the same position as antenna 33 according to Example 7. Antenna 34 is disposed on the vehicle interior side of the rear glass 13 included in the rear region and is disposed in the second peripheral region. Antenna 34 is disposed close to the pillar 11rc of the vehicle 10. Also, antenna 34 is disposed close to the lower edge portion 11rf of the rear glass 13.

[0108] Next, the communication capacity of the vehicle antenna system 170 will be described. Since the evaluation method is the same as that in Example 3, the description thereof will be omitted. The following settings were made for the vehicle antenna system 170, the default configuration 1, and the default configuration 2. Distance D24: 1470 [mm] Distance D13: 1530 [mm]

[0109] As a result of calculating the communication capacity, the communication capacity of the vehicle antenna system 170 with respect to the default configuration 1 was 105 [%]. Also, the communication capacity of the vehicle antenna system 170 with respect to the default configuration 2 was 115 [%].

[0110] As described above, the vehicle antenna system 170 according to Example 8 can improve the communication capacity as compared with the default configuration 1 and the default configuration 2.

[0111] [Example 9] Next, with reference to FIG. 12, a configuration example of the vehicle antenna system 180 according to Example 9 will be described. FIG. 12 is a top view of the vehicle of the vehicle antenna system according to Example 9. Example 9 is a specific example of Example 1 and also a specific example of Example 2. In Example 9, the antennas 31 and 34 are arranged at the same positions as in Example 3, and the antennas 32 and 33 are arranged at the same positions as in Example 5. In Example 9, a first antenna group including the first antenna 31 and the third antenna 34 is arranged in the front region, and a second antenna group including the second antenna 32 and the fourth antenna 33 is arranged in the rear region. Further, in Example 9, the first antenna group is arranged in at least one of the first peripheral region and the second peripheral region, and the second antenna group is arranged in the central region.

[0112] The antenna 31 is arranged at the same position as the antenna 31 according to Example 3. The antenna 31 is arranged on the inner surface side of the windshield 12 included in the front region and is arranged in the first peripheral region. The antenna 31 is arranged close to the pillar 11wa of the vehicle 10. Also, the antenna 31 is arranged close to the upper edge portion 11we of the windshield 12.

[0113] The antenna 32 is arranged at the same position as the antenna 32 according to Example 5. The antenna 32 is arranged on the inner surface side of the rear glass 13 included in the rear region and is arranged in the central region. The antenna 32 is arranged close to the upper edge portion 11re of the rear glass 13.

[0114] The antenna 33 is arranged at the same position as the antenna 33 according to Example 5. The antenna 33 is arranged on the inner surface side of the rear glass 13 included in the rear region and is arranged in the central region. The antenna 33 is arranged close to the upper edge portion 11re of the rear glass 13.

[0115] Antenna 34 is arranged at the same position as the antenna 34 according to Example 3. Antenna 34 is arranged on the vehicle interior side of the windshield 12 included in the front region and is arranged in the second peripheral region. Antenna 34 is arranged close to the pillar 11wc of the vehicle 10. Also, antenna 33 is arranged close to the upper edge portion 11we of the windshield 12.

[0116] Next, the communication capacity of the vehicle antenna system 180 will be described. Since the evaluation method is the same as that in Example 3, the description will be omitted. The following settings were made for the vehicle antenna system 180, the default configuration 1, and the default configuration 2. Distance D24: 700 [mm] Distance D13: 1470 [mm]

[0117] As a result of calculating the communication capacity, the communication capacity of the vehicle antenna system 180 with respect to the default configuration 1 was 109 [%]. Also, the communication capacity of the vehicle antenna system 180 with respect to the default configuration 2 was 125 [%].

[0118] As described above, the vehicle antenna system 180 according to Example 9 can improve the communication capacity as compared with the default configuration 1 and the default configuration 2.

[0119] [Example 10] Next, with reference to FIG. 13, a configuration example of the vehicle antenna system 190 according to Example 10 will be described. FIG. 13 is a top view of the vehicle of the vehicle antenna system according to Example 10. Example 10 is a specific example of Example 1 and also a specific example of Example 2. In Example 10, the positions where the antennas 31 and 34, which are vertical polarization antennas in Example 9, are arranged and the positions where the antennas 32 and 33, which are horizontal polarization antennas, are arranged are interchanged. In Example 10, a first antenna group including the first antenna 31 and the third antenna 34 is arranged in the front region, and a second antenna group including the second antenna 32 and the fourth antenna 33 is arranged in the rear region. Further, in Example 10, the first antenna group is arranged in at least one of the first peripheral region and the second peripheral region, and the second antenna group is arranged in the central region.

[0120] The antenna 31 is arranged at the same position as the antenna 32 according to Example 9. The antenna 31 is arranged on the inner surface side of the rear glass 13 included in the rear region and also in the central region. The antenna 31 is arranged close to the upper edge portion 11re of the edge portion of the rear glass 13.

[0121] The antenna 32 is arranged at the same position as the antenna 31 according to Example 9. The antenna 32 is arranged on the inner surface side of the windshield 12 included in the front region and also in the first peripheral region. The antenna 32 is arranged close to the pillar 11wa of the vehicle 10. Further, the antenna 32 is arranged close to the upper edge portion 11we of the edge portion of the windshield 12.

[0122] The antenna 33 is arranged at the same position as the antenna 34 according to Example 9. The antenna 33 is arranged on the inner surface side of the windshield 12 included in the front region and also in the second peripheral region. The antenna 33 is arranged close to the pillar 11wc of the vehicle 10. Further, the antenna 33 is arranged close to the upper edge portion 11we of the windshield 12.

[0123] Antenna 34 is arranged at the same position as antenna 33 according to Example 9. Antenna 34 is arranged on the vehicle interior side of the rear glass 13 included in the rear region and is arranged in the central region. Antenna 34 is arranged close to the upper edge portion 11re of the rear glass 13.

[0124] Next, the communication capacity of the vehicle antenna system 190 will be described. Since the evaluation method is the same as that in Example 3, the description will be omitted. The following settings were made for the vehicle antenna system 190, the default configuration 1, and the default configuration 2. Distance D24: 1470 [mm] Distance D13: 700 [mm]

[0125] As a result of calculating the communication capacity, the communication capacity of the vehicle antenna system 190 with respect to the default configuration 1 was 103 [%]. Also, the communication capacity of the vehicle antenna system 190 with respect to the default configuration 2 was 118 [%].

[0126] As described above, the vehicle antenna system 190 according to Example 10 can improve the communication capacity as compared with the default configuration 1 and the default configuration 2.

[0127] [Example 11] Subsequently, with reference to FIG. 14, a configuration example of the vehicle antenna system 200 according to Example 11 will be described. FIG. 14 is a top view of the vehicle of the vehicle antenna system according to Example 11. Example 11 is a specific example of Example 1 and is also a specific example of Example 2. In Example 11, antenna 31 and antenna 34 are arranged at the same positions as in Example 4, and antenna 32 and antenna 33 are arranged at the same positions as in Example 6. In Example 11, a first antenna group including antenna 31 as the first antenna and antenna 34 as the third antenna is arranged in the front region, and a second antenna group including antenna 32 as the second antenna and antenna 33 as the fourth antenna is arranged in the rear region. Further, in Example 11, the first antenna group is arranged in the central region, and the second antenna group is arranged in at least one of the first peripheral region and the second peripheral region.

[0128] Antenna 31 is disposed at the same position as antenna 31 according to Example 4. Antenna 31 is disposed on the vehicle interior surface side of windshield 12 included in the front region and is disposed in the central region. Antenna 31 is disposed close to the upper edge portion 11we of windshield 12.

[0129] Antenna 32 is disposed at the same position as antenna 32 according to Example 6. Antenna 32 is disposed on the vehicle interior surface side of rear glass 13 included in the rear region and is disposed in the first peripheral region. Antenna 32 is disposed close to pillar 11ra of vehicle 10. Further, antenna 32 is disposed close to the lower edge portion 11rf of the edge of rear glass 13.

[0130] Antenna 33 is disposed at the same position as antenna 33 according to Example 6. Antenna 33 is disposed on the vehicle interior surface side of rear glass 13 included in the rear region and is disposed in the second peripheral region. Antenna 33 is disposed close to pillar 11rc of vehicle 10. Further, antenna 33 is disposed close to the lower edge portion 11rf of the edge of rear glass 13.

[0131] Antenna 34 is disposed at the same position as antenna 34 according to Example 4. Antenna 34 is disposed on the vehicle interior surface side of windshield 12 included in the front region and is disposed in the central region. Antenna 34 is disposed close to the upper edge portion 11we of the edge of windshield 12.

[0132] Next, the communication capacity of vehicle antenna system 200 will be described. Since the evaluation method is the same as that of Example 3, the description thereof will be omitted. The following settings were made for vehicle antenna system 200, default configuration 1, and default configuration 2. Distance D24: 1470 [mm] Distance D13: 345 [mm]

[0133] As a result of calculating the communication capacity, the communication capacity of the vehicle antenna system 200 for the default configuration 1 was 122 [%]. Further, the communication capacity of the vehicle antenna system 200 for the default configuration 2 was 131 [%].

[0134] As described above, the vehicle antenna system 200 according to Example 11 can improve the communication capacity as compared with the default configuration 1 and the default configuration 2.

[0135] [Example 12] Subsequently, with reference to FIG. 15, a configuration example of the vehicle antenna system 210 according to Example 12 will be described. FIG. 15 is a top view of a vehicle of the vehicle antenna system according to Example 12. Example 12 is a specific example of Example 1 and also a specific example of Example 2. Example 12 has a configuration in which the positions where the antennas 31 and 34, which are vertical polarization antennas in Example 11, are arranged and the positions where the antennas 32 and 33, which are horizontal polarization antennas, are arranged are interchanged. In Example 12, a first antenna group including the first antenna 31 and the third antenna 34 is arranged in the rear region, and a second antenna group including the second antenna 32 and the fourth antenna 33 is arranged in the front region. Further, in Example 12, the first antenna group is arranged in at least one of the first peripheral region and the second peripheral region, and the second antenna group is arranged in the central region.

[0136] The antenna 31 is arranged at the same position as the antenna 32 according to Example 11. The antenna 31 is arranged on the inner surface side of the rear glass 13 included in the rear region and is arranged in the first peripheral region. The antenna 31 is arranged close to the pillar 11ra of the vehicle 10. The antenna 31 is arranged close to the lower edge portion 11rf of the edge of the rear glass 13.

[0137] The antenna 32 is arranged at the same position as the antenna 31 according to Example 11. The antenna 32 is arranged on the inner surface side of the windshield 12 included in the front region and is arranged in the central region. The antenna 32 is arranged close to the upper edge portion 11we of the edge of the windshield 12.

[0138] Antenna 33 is disposed at the same position as antenna 34 according to Example 11. Antenna 33 is disposed on the inner surface side of the windshield 12 included in the front region and in the central region. Antenna 33 is disposed close to the upper edge 11we of the edge of the windshield 12.

[0139] Antenna 34 is disposed at the same position as antenna 33 according to Example 11. Antenna 34 is disposed on the inner surface side of the rear glass 13 included in the rear region and in the second peripheral region. Antenna 34 is disposed close to the pillar 11rc of the vehicle 10. Antenna 34 is disposed close to the lower edge 11rf of the edge of the rear glass 13.

[0140] Next, the communication capacity of the vehicle antenna system 210 will be described. Since the evaluation method is the same as that in Example 3, the description thereof will be omitted. The following settings were made for the vehicle antenna system 210, the default configuration 1, and the default configuration 2. Distance D24: 345 [mm] Distance D13: 1470 [mm]

[0141] As a result of calculating the communication capacity, the communication capacity of the vehicle antenna system 210 with respect to the default configuration 1 was 106 [%]. Also, the communication capacity of the vehicle antenna system 210 with respect to the default configuration 2 was 114 [%].

[0142] As described above, the vehicle antenna system 210 according to Example 12 can improve the communication capacity as compared with the default configuration 1 and the default configuration 2.

[0143] [Example 13] Next, with reference to FIG. 16, a configuration example of the vehicle antenna system 220 according to Example 13 will be described. FIG. 16 is a top view of the vehicle of the vehicle antenna system according to Example 13. Example 13 is a specific example of Example 2. In Example 13, the antennas 31 and 34 are arranged at the same positions as those of the antenna 31 in Example 4, and the antennas 32 and 33 are arranged at the same positions as those of the antenna 32 in Example 5. In Example 13, a first antenna group including the antenna 31 as the first antenna and the antenna 34 as the third antenna is arranged in the front region, and a second antenna group including the antenna 32 as the second antenna and the antenna 33 as the fourth antenna is arranged in the rear region.

[0144] The antenna 31 is arranged at the same position as the antenna 31 according to Example 4. The antenna 31 is arranged on the inner surface side of the windshield 12 included in the front region and in the central region. The antenna 31 is arranged close to the upper edge portion 11we of the windshield 12.

[0145] The antenna 32 is arranged at the same position as the antenna 32 according to Example 5. The antenna 32 is arranged on the inner surface side of the rear glass 13 included in the rear region and in the central region. The antenna 32 is arranged close to the upper edge portion 11re of the edge portion of the rear glass 13.

[0146] The antenna 33 is arranged at the same position as the antenna 33 according to Example 5. The antenna 33 is arranged on the inner surface side of the rear glass 13 included in the rear region and in the central region. The antenna 33 is arranged close to the upper edge portion 11re of the edge portion of the rear glass 13.

[0147] The antenna 34 is arranged at the same position as the antenna 34 according to Example 4. The antenna 34 is arranged on the inner surface side of the windshield 12 included in the front region and in the central region. The antenna 34 is arranged close to the upper edge portion 11we of the edge portion of the windshield 12.

[0148] Next, the communication capacity of the vehicle antenna system 220 will be described. Since the evaluation method is the same as in Example 3, the description thereof will be omitted. The following settings were made for the vehicle antenna system 220, Default Configuration 1, and Default Configuration 2. Distance D24: 700 [mm] Distance D13: 345 [mm]

[0149] As a result of calculating the communication capacity, the communication capacity of the vehicle antenna system 220 with respect to Default Configuration 1 was 122 [%]. Also, the communication capacity of the vehicle antenna system 220 with respect to Default Configuration 2 was 132 [%].

[0150] As described above, the vehicle antenna system 220 according to Example 13 can improve the communication capacity as compared with Default Configuration 1 and Default Configuration 2.

[0151] [Example 14] Subsequently, with reference to FIG. 17, a configuration example of the vehicle antenna system 230 according to Example 14 will be described. FIG. 17 is a top view of the vehicle of the vehicle antenna system according to Example 14. Example 14 is a specific example of Example 2. Example 14 has a configuration in which the positions where the antennas 31 and 34, which are the vertical polarization antennas in Example 13, are arranged and the positions where the antennas 32 and 33, which are the horizontal polarization antennas, are arranged are interchanged. Example 14 has a configuration in which a first antenna group including the antenna 31 as the first antenna and the antenna 34 as the third antenna is arranged in the rear region, and a second antenna group including the antenna 32 as the second antenna and the antenna 33 as the fourth antenna is arranged in the front region.

[0152] The antenna 31 is arranged at the same position as the antenna 32 according to Example 13. The antenna 31 is arranged on the rear glass 13 included in the rear region and also in the central region. The antenna 31 is arranged in the vicinity of the upper edge 11re of the edge of the rear glass 13.

[0153] Antenna 32 is arranged at the same position as antenna 31 according to Example 13. Antenna 32 is arranged on the vehicle interior surface side of the windshield 12 included in the front region and is arranged in the central region. Antenna 32 is arranged close to the upper edge 11we of the edge of the windshield 12.

[0154] Antenna 33 is arranged at the same position as antenna 34 according to Example 13. Antenna 33 is arranged on the vehicle interior surface side of the windshield 12 included in the front region and is arranged in the central region. Antenna 33 is arranged close to the upper edge 11we of the edge of the windshield 12.

[0155] Antenna 34 is arranged at the same position as antenna 33 according to Example 13. Antenna 34 is arranged on the vehicle interior surface side of the rear windshield 13 included in the rear region and is arranged in the central region. Antenna 34 is arranged close to the upper edge 11re of the rear windshield 13.

[0156] Next, the communication capacity of the vehicle antenna system 230 will be described. Since the evaluation method is the same as that in Example 3, the description will be omitted. The following settings were made for the vehicle antenna system 230, the default configuration 1, and the default configuration 2. Distance D24: 345 [mm] Distance D13: 700 [mm]

[0157] As a result of calculating the communication capacity, the communication capacity of the vehicle antenna system 230 for the default configuration 1 was 109 [%]. Also, the communication capacity of the vehicle antenna system 230 for the default configuration 2 was 118 [%].

[0158] As described above, the vehicle antenna system 230 according to Example 14 can improve the communication capacity as compared with the default configuration 1 and the default configuration 2.

[0159] Next, the evaluation results of the communication capacity of the vehicle antenna systems according to Examples 3 to 14 will be described. Table 1 summarizes the relative results of the communication capacity of the vehicle antenna systems according to Examples 3 to 14. The second to fifth columns from the left in Table 1 indicate which of the vertical polarization (V polarization) or horizontal polarization (H polarization) Antenna 31 to Antenna 34 correspond to, respectively. Further, the positions where Antenna 31 to Antenna 34 are arranged are described in the second to fifth columns. WS represents the windshield, RG represents the rear glass, the center represents the central region, the first periphery represents the first peripheral region, and the second periphery represents the second peripheral region. For example, since the position where Antenna 31 according to Example 3 is arranged is the windshield and the first peripheral region, it is described as WS and the center in the following table. [Table 1]

[0160] As shown in Table 1, the vehicle antenna systems 120 to 230 had numerical values exceeding 100[%] for the communication capacity with respect to the default configuration 1 and the default configuration 2. Therefore, the vehicle antenna systems 120 to 230 can improve the communication capacity with respect to the default configuration 1 with all antennas having vertical polarization and the default configuration 2 with all antennas having horizontal polarization.

[0161] In addition, the vehicle antenna systems 120 to 230 are specific examples of the vehicle antenna systems according to Example 1 and Example 2. Therefore, for the vehicle antenna system according to the embodiment, as in Example 1, by configuring the first antenna and the second antenna such that (1) one is disposed in the central region and the other is disposed in the first peripheral region or the second peripheral region, the communication capacity can be improved. Further, for the vehicle antenna system according to the embodiment, as in Example 2, by configuring the first antenna and the second antenna such that (2) one is disposed in the first region and the other is disposed in the second region, the communication capacity can be improved. Furthermore, for the vehicle antenna system according to the embodiment, even with a configuration combining Example 1 and Example 2, the communication capacity can be improved. That is, for the vehicle antenna system according to the embodiment, the communication capacity can be improved by disposing the first antenna and the second antenna based on at least one of the above (1) and (2).

[0162] Next, the comparison results of the communication capacities of the vehicle antenna systems 120 to 230 will be described. To compare the communication capacities of the vehicle antenna systems 120 to 230, the communication capacities of the vehicle antenna systems 120 to 230 with respect to the default configuration 1 in Example 3 were calculated. Table 2 shows the comparison results of the communication capacities of the vehicle antenna systems according to each example. Among Table 2, the columns other than the rightmost column correspond to Table 1. In the rightmost column, the communication capacities of the vehicle antenna systems according to each example with respect to the communication capacity of the default configuration 1 in Example 3 are described.

Table 2

[0163] As shown in Table 2, among the vehicle antenna systems according to Examples 3 to 14, the communication capacity of the vehicle antenna system 130 according to Example 4 increased the most. The vehicle antenna system 130 according to Example 4 has a configuration in which antennas 31 to 34 are arranged on the windshield 12. By arranging the antennas 31 to 34 on the windshield 12 in the front facing the traveling direction of the vehicle 10, the antennas 31 to 34 can receive more radio waves transmitted from a communication device (not shown) facing the vehicle antenna system 130.

[0164] Specifically, the radio waves transmitted from the communication device are reflected by a building or the like and reach the antennas 31 to 34 as a plurality of radio waves due to multipath. By arranging the antennas 31 to 34 on the windshield 12 in the front facing the traveling direction of the vehicle 10, more radio waves can be received than when arranged on the rear glass 13, so the antenna gain of the antennas 31 to 34 can also be improved. Therefore, it is considered that the communication capacity of the vehicle antenna system 130 has a higher value than the example in which at least one of the antennas 31 to 34 is arranged on the rear glass 13.

[0165] Here, in the vehicle antenna system 120 according to Example 3, the antennas 31 to 34 are also arranged on the windshield 12. However, the antennas 31 and 34, which are vertical polarization antennas, are arranged close to the pillar 11wa and the pillar 11wc. On the other hand, in the vehicle antenna system 130 according to Example 4, the antennas 32 and 33, which are horizontal polarization antennas, are arranged close to the pillar 11wa and the pillar 11wc. By arranging the horizontal polarization antennas at positions close to the pillar, the horizontal polarization antennas can receive radio waves through the pillar. That is, the antennas 32 and 33, which are horizontal polarization antennas, can receive radio waves through the pillar 11wa and the pillar 11wc. As a result, the antenna gains of the antennas 32 and 33 according to Example 4 are considered to be higher than those of the antennas 31 and 34 according to Example 3, and the communication capacity is increased. Therefore, it was confirmed that by arranging the antennas 31 to 34 as in the vehicle antenna system 130 according to Example 4, a higher communication capacity can be achieved.

[0166] As described above, the antennas 31 and 34 of the MIMO antenna 30 are configured as vertical polarization antennas, the antennas 32 and 33 are configured as horizontal polarization antennas, and by being distributed and arranged on the vehicle 10, the communication capacity can be improved. Therefore, according to the vehicle antenna system according to the embodiment, the communication capacity can be improved.

[0167] As described above, the present invention has been described with reference to the above embodiments. However, the present invention is not limited only to the configurations of the above embodiments, and of course includes various modifications, corrections, and combinations that can be made by those skilled in the art within the scope of the invention of the claims of the present patent application.

[0168] This application claims priority based on Japanese Patent Application No. 2021-017622 filed on February 5, 2021, and incorporates the entire disclosure thereof herein.

Description of Reference Numerals

[0169] 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230 Vehicle Antenna System 10 Vehicle 11 Metal Body 11wa, 11wc, 11ra, 11rc Pillars 11wb, 11wd, 11rb, 11rd Edges 11we, 11re Upper Edges 11rf Lower Edge 12 Windshield 13 Rear Glass 20, 30 MIMO Antenna 21~24, 31~34 Antennas 21a Power Feeding Unit 21b, 21c Antenna Elements C Center Line B1, B2 Boundary Lines B3 Reference Line

Claims

1. A vehicle and a MIMO antenna mounted on the vehicle for transmitting and receiving radio waves of a predetermined frequency, wherein the MIMO antenna has four antennas including a first antenna mainly transmitting and receiving a first polarization wave, a second antenna mainly transmitting and receiving a second polarization wave orthogonal to the first polarization wave, a third antenna mainly transmitting and receiving the first polarization wave, and a fourth antenna mainly transmitting and receiving the second polarization wave, the four antennas are arranged on a windshield or the four antennas are arranged on a rear glass, when, from a viewpoint in the vertical direction of the vehicle, a region having a width equidistant in the left and right vehicle width directions with respect to a center line bisecting the vehicle width is defined as a central region, and two regions sandwiching the central region are defined as a first peripheral region and a second peripheral region, and an antenna group including the first antenna and the third antenna is defined as a first antenna group, and an antenna group including the second antenna and the fourth antenna is defined as a second antenna group, one of the first antenna group and the second antenna group is arranged in the central region and the other is arranged in at least one of the first peripheral region and the second peripheral region, when the predetermined frequency is λ, the wavelength shortening rate of the dielectric to which the first antenna and the third antenna are attached is k1, and the wavelength shortening rate of the dielectric to which the second antenna and the fourth antenna are attached is k2, the distance between the first antenna and the third antenna is k1×λ / 2 or more, the distance between the second antenna and the fourth antenna is k2×λ / 2 or more, An antenna system for a vehicle.

2. the first antenna and the third antenna are arranged in the central region, the second antenna is arranged in the first peripheral region, and the fourth antenna is arranged in the second peripheral region, or the first antenna is arranged in the first peripheral region, the third antenna is arranged in the second peripheral region, and the second antenna and the fourth antenna are arranged in the central region, The vehicle antenna system according to claim 1.

3. the first antenna and the third antenna are arranged at the same distance from the center line, the second antenna and the fourth antenna are arranged at the same distance from the center line, The vehicle antenna system according to claim 2.

4. the first polarization wave is a vertical polarization wave and the second polarization wave is a horizontal polarization wave, The first antenna and the third antenna are vertical polarization antennas that mainly transmit and receive vertically polarized waves. The second antenna and the fourth antenna are horizontal polarization antennas that mainly transmit and receive horizontally polarized waves. The vehicle antenna system according to any one of claims 1 to 3. **Claim 5** The width W of the central region Ｃ is, when the width of the vehicle is W, 0.1 × W ≤ W Ｃ ≤ 0.5 × W The vehicle antenna system according to any one of claims 1 to 4, satisfying **Claim 6** Among the MIMO antennas, the antennas arranged in either the first peripheral region or the second peripheral region are arranged at a distance within 100 mm from the pillar of the vehicle. The vehicle antenna system according to any one of claims 1 to 5. **Claim 7** The predetermined frequency is 3.3 GHz or higher. The vehicle antenna system according to any one of claims 1 to 6. **Claim 8** The predetermined frequency is 6 GHz or lower. The vehicle antenna system according to any one of claims 1 to 7.

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