阅读说明：本技术 天线、天线装置、以及车载用天线装置 (Antenna, antenna device, and vehicle-mounted antenna device ) 是由 原文平 于 2019-10-09 设计创作，主要内容包括：本发明的天线(100)具有：地板(110)；和辐射振子(130),该辐射振子(130)为向规定的扩开方向扩开的形状,并为以与作为馈电部的馈电线(151)连接的端部(135)为基准的自相似形状。辐射振子(130)将端部(135)朝向地板(110)并以相对于端部(135)立起的状态下配置。并且,辐射振子(130)具有隔着沿扩开方向的规定虚拟对称面(A1)而成为面对称的第1辐射振子部(131)以及第2辐射振子部(133),由此构成向扩开方向扩开的形状。(An antenna (100) of the present invention comprises: a floor (110); and a radiation oscillator (130), wherein the radiation oscillator (130) is in a shape of expanding in a predetermined expanding direction, and is in a self-similar shape with an end (135) connected to a feed line (151) as a feed portion as a reference. The radiation oscillator (130) is arranged in a state in which the end section (135) faces the floor (110) and is raised with respect to the end section (135). The radiation oscillator (130) has a shape that is expanded in the expansion direction by having a1 st radiation oscillator unit (131) and a2 nd radiation oscillator unit (133) that are plane-symmetric with a predetermined virtual plane of symmetry (A1) along the expansion direction in between.)

1. An antenna, characterized in that it comprises a base,

a radiation oscillator having a shape expanding in a predetermined expanding direction, the radiation oscillator being arranged in a state of rising from an end portion connected to the power feeding portion,

the radiator element has a1 st radiator element section and a2 nd radiator element section which are plane-symmetric with respect to a predetermined virtual plane of symmetry in the expansion direction, and the expanded shape is formed in a self-similar shape with respect to the end section.

2. The antenna of claim 1,

the opening degree of the expansion of the 1 st radiation element part and the 2 nd radiation element part is 20 degrees or more and 160 degrees or less.

3. The antenna of claim 1 or 2,

the 1 st radiation element unit and the 2 nd radiation element unit are integrally formed by a predetermined bent portion located on the virtual symmetrical plane.

4. The antenna of claim 3,

the spread shape is a V-shape bent at the bent portion in a plan view of the 1 st radiation element portion and the 2 nd radiation element portion.

5. The antenna of claim 3 or 4,

the bent portion has a straight bent line,

the length of the radiation element in the direction of the zigzag line in the projection view onto the virtual symmetry plane is equal to or longer than 1/8 wavelength of the lower limit radio wave of the antenna band frequency.

6. The antenna of claim 1 or 2,

the 1 st radiation element unit and the 2 nd radiation element unit are integrally configured so as not to include a part of a predetermined virtual bent portion located on the virtual symmetrical plane.

7. The antenna of claim 6,

the expanding shape is a V-shape with the end portion as a base point when the 1 st radiation element portion and the 2 nd radiation element portion are projected to the end portion side in a plan view.

8. The antenna of claim 6 or 7,

the virtual bending portion has a linear virtual bending line,

the length of the radiation element in the direction of the virtual zigzag line in the projection view onto the virtual symmetry plane is equal to or longer than 1/8 wavelengths of a lower limit radio wave of an antenna band frequency.

9. The antenna of claim 5 or 8,

the lower limit of the antenna band frequency is more than 1 GHz.

10. An antenna device, characterized in that,

having a plurality of antennas as claimed in any one of claims 1 to 9.

11. An antenna device, characterized in that,

a plurality of antennas as claimed in any one of claims 1 to 9, with the direction of the spread being directed in different directions.

12. An on-vehicle antenna device is characterized by comprising:

the antenna of any one of claims 1-9;

other antennas for broadcast reception having an antenna band frequency lower than that of the antenna; and

a housing accommodating the antenna and the other antennas.

13. An antenna, characterized in that it comprises a base,

a radiation oscillator having a shape expanding in a predetermined expanding direction, the radiation oscillator being arranged in a state of rising from an end portion connected to the power feeding portion,

the radiator element has a1 st radiator element section and a2 nd radiator element section which are plane-symmetric with respect to a predetermined virtual plane of symmetry in the expansion direction,

the angle formed by the end part and the 1 st radiation pendulum part is an acute angle,

the angle formed by the end part and the 2 nd radiation pendulum part is an acute angle.

Technical Field

The invention relates to an antenna, an antenna device, and a vehicle-mounted antenna device.

Background

As an antenna having a broadband characteristic, there is a self-similar antenna having a self-similar shape. For example, a bow-tie antenna, which is one of self-similar antennas, is known as a wide band antenna capable of stably operating in a wide band of about 600MHz to 6 GHz.

Patent document 1 discloses an antenna device using a bow-tie antenna.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2002-43838

Disclosure of Invention

One of the characteristics of bow-tie antennas is non-directivity. Thus, a bow-tie antenna may be an option when designing an antenna with non-directional and broadband characteristics. However, when designing an antenna that needs to have broadband characteristics and also needs to improve gain in a desired direction, it is difficult to design an antenna that can be designed by applying only a technique of directly applying a conventional self-similar antenna including a conventional bow tie antenna.

An object of the present invention is to provide a technique for realizing a wide band antenna capable of improving a gain in a desired direction.

A first aspect of the present invention for solving the above problems is an antenna including a radiation element arranged in a state of standing on an end portion connected to a power feeding portion and having a shape of expanding in a predetermined expanding direction, the radiation element including a1 st radiation element portion and a2 nd radiation element portion which are plane-symmetric with respect to a predetermined virtual plane of symmetry along the expanding direction, the expanding shape being configured to have a self-similar shape with the end portion as a reference.

According to the first aspect, the radiation element can be formed in a shape that is expanded in a predetermined expansion direction and a self-similar shape with respect to an end portion connected to the power feeding portion, and the radiation element can be arranged in a state of being erected with respect to the end portion, thereby forming the antenna. According to the antenna of this aspect, the gain in the spreading direction can be improved. Therefore, the directivity of the antenna can be controlled by the direction of the spreading direction, and a broadband antenna in which the gain in a desired direction is improved can be realized.

In the 2 nd aspect, in the antenna according to the 1 st aspect, the opening degree of the 1 st radiation element portion and the 2 nd radiation element portion is 20 degrees or more and 160 degrees or less.

According to the 2 nd aspect, the opening degree in the expanding direction formed by the expanded shape of the radiation oscillator can be set to 20 degrees or more and 160 degrees or less.

In the antenna according to claim 3, in the antenna according to claim 1 or 2, the 1 st radiating element portion and the 2 nd radiating element portion are integrally formed by a predetermined bent portion located on the virtual symmetrical plane.

According to the 3 rd aspect, the 1 st radiation element section and the 2 nd radiation element section which are integrally configured can be bent at the bent section, and the radiation element can be expanded at a predetermined opening degree.

In the antenna according to claim 4, in the antenna according to claim 3, the spread-out shape is a V-shape bent at the bent portion when the 1 st radiation element portion and the 2 nd radiation element portion are viewed in plan.

According to the 4 th aspect, the spread shape can be a V-shape bent at the bent portion in a plan view of the 1 st radiation element unit and the 2 nd radiation element unit.

In the antenna according to claim 5 or 4, the bent portion has a straight bent line, and the length of the radiation element in the direction of the bent line in a projection view onto the virtual symmetry plane is equal to or longer than 1/8 wavelength of a lower limit radio wave of an antenna band frequency.

According to the 5 th aspect, the length of the radiation element in the direction along the zigzag line when viewed in projection onto the virtual symmetry plane can be set to be equal to or longer than 1/8 wavelengths.

In the antenna according to claim 6, in the antenna according to claim 1 or 2, the 1 st radiating element portion and the 2 nd radiating element portion are integrally configured so as not to include a part of a predetermined virtual bent portion located on the virtual symmetrical plane.

According to the 6 th aspect, the 1 st radiation element section and the 2 nd radiation element section, which are integrally configured, can be bent so as not to include a part of the virtual bent section, and thereby the radiation element can be expanded by a predetermined opening degree.

In the antenna according to claim 7, in the antenna according to claim 6, when the 1 st radiation element portion and the 2 nd radiation element portion are projected to the end portion side in a plan view, the spread shape is a V-shape with the end portion as a base point.

According to the 7 th aspect, the spread shape can be a V-shape with the end portion as a base point in a plan view of the 1 st radiating element portion and the 2 nd radiating element portion.

In the 8 th aspect, in the antenna according to the 6 th or 7 th aspect, the virtual meander portion has a linear virtual meander line, and a length of the radiation element in a direction of the virtual meander line in a projection view onto the virtual symmetry plane is equal to or longer than 1/8 wavelengths of a lower limit radio wave of an antenna band frequency.

According to the 8 th aspect, the length of the radiation element in the direction along the virtual zigzag line when viewed in projection onto the virtual symmetry plane can be set to be equal to or longer than 1/8 wavelengths.

The 9 th aspect is the antenna according to the 5 th or 8 th aspect, wherein the lower limit of the antenna band frequency is 1GHz or more.

According to the 9 th aspect, the antenna band frequency can be set to 1GHz or more.

The 10 th aspect is an antenna device including a plurality of antennas of any one of the 1 st to 9 th aspects.

According to the 10 th aspect, an antenna device including a plurality of antennas according to any one of the 1 st to 9 th aspects can be realized.

The 11 th aspect is an antenna device having a plurality of antennas of any one of the 1 st to 9 th aspects with the spreading directions directed in different directions.

According to the 11 th aspect, the antenna device can be configured by disposing the plurality of antennas of any one of the 1 st to 9 th aspects so that the spreading directions thereof face different directions. Accordingly, the gain in the spreading direction can be increased by each antenna, and thus, for example, by adjusting the number of antennas and/or the spreading direction of each antenna so as to cover all directions in a predetermined plane, an antenna device having characteristics of high gain and no directivity can be realized in a wide band.

In a 12 th aspect, an in-vehicle antenna device includes: the antenna of any one of modes 1 to 9; other antennas for broadcast reception having an antenna band frequency lower than that of the antenna; and a housing accommodating the antenna and the other antennas.

According to the 12 th aspect, it is possible to realize an in-vehicle antenna device in which an antenna that achieves the same effect as any one of the 1 st to 9 th aspects and another antenna for broadcast reception having a lower frequency band than the antenna are housed in a case.

A 13 th aspect is an antenna including a radiation element arranged in a state of standing on an end portion connected to a power feeding portion and having a shape of expanding in a predetermined expanding direction, the radiation element including a1 st radiation element portion and a2 nd radiation element portion which are plane-symmetric with respect to a predetermined virtual plane of symmetry along the expanding direction, the expanding shape being configured such that an angle formed between the end portion and the 1 st radiation element portion is an acute angle and an angle formed between the end portion and the 2 nd radiation element portion is an acute angle.

According to the 13 th aspect, the antenna can be configured by forming the radiation element in a shape that is expanded in a predetermined expansion direction, forming the end portion at an acute angle with respect to the 1 st radiation element portion, forming the end portion at an acute angle with respect to the 2 nd radiation element portion, and disposing the radiation element in a state of being raised with respect to the end portion. According to the antenna of this aspect, the gain in the spreading direction can be improved. Therefore, the directivity of the antenna can be controlled by the direction of the spreading direction, and a wide-band antenna in which the gain in a desired direction is improved can be realized.

Drawings

Fig. 1 is a diagram showing an internal configuration example of an in-vehicle antenna device.

Fig. 2 is a diagram showing an example of the configuration of one antenna in the antenna device.

Fig. 3 is an explanatory diagram for explaining basic characteristics of the antenna.

Fig. 4 is another explanatory diagram for explaining the basic characteristics of the antenna.

Fig. 5 is another explanatory diagram for explaining the basic characteristics of the antenna.

Fig. 6 is another diagram showing an example of the configuration of an antenna in the antenna device.

Fig. 7 is a plan view of the antenna in a case where the opening δ is 180 degrees.

Fig. 8 is a plan view of the antenna when the opening δ is 120 degrees.

Fig. 9 is a plan view of the antenna when the opening δ is 90 degrees.

Fig. 10 is a plan view of the antenna in a case where the opening δ is 60 degrees.

Fig. 11 is a plan view of the antenna in a case where the opening δ is set to 20 degrees.

Fig. 12 is a diagram showing a directivity pattern when the frequency is 1700 MHz.

Fig. 13 is a diagram showing a directivity pattern when the operating frequency is 2500 MHz.

Fig. 14 is a diagram showing a directivity pattern when the operating frequency is 3500 MHz.

Fig. 15 is a diagram showing a directivity pattern when the operating frequency is 4500 MHz.

Fig. 16 is a diagram showing a directivity pattern when the operating frequency is 5500 MHz.

Fig. 17 is a diagram showing a directivity pattern when the operating frequency is 6000 MHz.

Fig. 18 is a graph showing a characteristic of a pass loss between two antennas.

Fig. 19 is a graph showing the VSWR characteristics of the antenna.

Fig. 20 is a diagram showing an example of the configuration of an antenna according to a modification.

Fig. 21 is a diagram showing an example of the configuration of an antenna device having a plurality of antennas of fig. 20.

Fig. 22 is a graph showing envelope correlation coefficients between two antennas.

Fig. 23 is a graph showing a characteristic of a pass loss between two antennas.

Fig. 24 is a graph showing the horizontal plane average gain.

Fig. 25 is a graph showing radiation efficiency.

Fig. 26 is a graph showing the VSWR characteristics.

Fig. 27 is a diagram showing a directivity pattern when the frequency is 1700 MHz.

Fig. 28 is a diagram showing a directivity pattern when the operating frequency is 2500 MHz.

Fig. 29 is a diagram showing a directivity pattern when the operating frequency is 3500 MHz.

Fig. 30 is a diagram showing a directivity pattern when the operating frequency is 4500 MHz.

Fig. 31 is a diagram showing a directivity pattern when the operating frequency is 5500 MHz.

Fig. 32 is a diagram showing a directivity pattern when the operating frequency is 6000 MHz.

Detailed Description

Hereinafter, an example of a preferred embodiment of the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments described below, and the embodiments to which the present invention can be applied are not limited to the embodiments described below. In the description of the drawings, the same reference numerals are given to the same parts.

First, in the present embodiment, the direction is defined as follows. That is, the in-vehicle antenna device 1 according to the present embodiment is mounted on a vehicle such as a passenger vehicle and used, and the front-rear, left-right, and up-down directions thereof are set to be the same as the front-rear, left-right, and up-down directions of the vehicle when mounted on the vehicle. The front-back direction is defined as the Y-axis direction, the left-right direction is defined as the X-axis direction, and the up-down direction is defined as the Z-axis direction. In order to make it easy to understand the directions of the three orthogonal axes, reference directions indicating directions parallel to the directions of the axes are marked in the drawings. The intersection of the reference directions shown in the figures does not mean the origin of coordinates. Only the reference direction is shown. The in-vehicle antenna device 1 according to the present embodiment is designed to have a narrow front side and a narrower left-right width as it goes upward from the mounting surface to the vehicle, so that the design features can contribute to the understanding of the direction.

Fig. 1 is a perspective view showing an internal configuration example of an in-vehicle antenna device 1 according to the present embodiment. As shown in fig. 1, the in-vehicle antenna device 1 is configured to accommodate a plurality of types of antennas in a space formed by an antenna case 11 and an antenna base 13 as a case. For example, the storage container contains: an antenna device 10 having two antennas 100(100-1, 100-2) that can be used as an antenna for wireless communication or the like; a broadcast antenna 20; a satellite broadcast antenna 30; and a gnss (global Navigation Satellite system) antenna 40.

More specifically, the antenna case 11 has a shape protruding upward at the center portion. That is, the antenna case 11 has a shark fin shape. Further, a capacitive load element 23 of the broadcasting antenna 20 is disposed above the internal space and inside the protruding portion, and a spiral element 21 is disposed below the capacitive load element 23. Two antennas 100-1 and 100-2 of the antenna device 10 are disposed on the bottom rear side of the internal space, and a satellite broadcast antenna 30 and a GNSS antenna 40 are disposed on the bottom front side of the internal space. The total height of the antennas 100-1 and 100-2 disposed in the in-vehicle antenna device 1, that is, the length from the antenna base 13 to the uppermost position, is lower than the total height of the broadcast antenna 20 for both the antennas 100-1 and 100-2. The antennas 100-1 and 100-2 may be disposed at a lower position than the broadcast antenna 20. The antennas 100-1 and 100-2 are disposed at a position rearward of the broadcast antenna 20.

The broadcast antenna 20 is, for example, a broadcast receiving antenna for receiving broadcast waves of AM broadcast transmission and FM broadcast transmission. The broadcast antenna 20 includes a spiral vibrator 21 formed by winding a conductor in a spiral shape, and a capacitive load vibrator 23 for applying a capacitance to the ground to the spiral vibrator 21, and resonates in the FM band with the spiral vibrator 21 via the capacitive load vibrator 23, and the AM band is received by the capacitive load vibrator 23. The antenna band frequency of the broadcast antenna 20 is lower than the antenna band frequency of the antenna arrangement 10. Therefore, it can be said that interference is less likely to occur between the antenna 100 and the broadcast antenna 20 (the other antenna for the antenna 100)) depending on the arrangement position or the frequency band.

The satellite broadcast antenna 30 is, for example, an antenna for receiving a broadcast wave broadcast by a satellite broadcast such as Sirius (Sirius) XM broadcast. As the satellite broadcast antenna 30, a planar antenna 31 such as a patch antenna shown in fig. 1 can be used, for example. As shown in fig. 1, the satellite broadcast antenna 30 can be configured by disposing the non-feeding element 32 on the planar antenna 31. Further, the type of the antenna is not limited thereto, and may be appropriately selected.

The GNSS antenna 40 is an antenna for receiving satellite signals transmitted from positioning satellites such as GPS satellites.

The antenna 100 is explained next. Fig. 2 is an enlarged view showing a configuration example of one antenna 100 (for example, the rear antenna 100-1) in the antenna device 10. As described in detail later, the antenna 100 of the present embodiment is configured such that the radiation element 130 is expanded in a predetermined expansion direction (in the example of fig. 2, in a rearward direction which is a negative direction of the Y axis), but in fig. 2, a completely expanded state is shown (a state in which the expansion degree δ is 180 degrees).

As shown in fig. 2, the antenna 100 has: a floor 110; and a radiation oscillator 130, wherein the radiation oscillator 130 is disposed in a state in which the end portion 135 is raised with respect to the floor 110 toward the floor 110, in other words, in a state in which the end portion 135 is raised with respect to the floor.

The floor panel 110 has a through hole 111 penetrating vertically (Z-axis direction). A power supply line is inserted into the insertion hole 111. An end 135 of the radiation oscillator 130 facing the floor 110 is connected to a power supply line 150 as a power supply unit at a position just above the insertion hole 111. When the power feeding line 150 is formed of a coaxial cable, the inner conductor 151 of the coaxial cable is connected to the end portion 135, and the outer conductor is connected to the floor 110.

The radiating element 130 has a self-similar shape with respect to the end 135. In a state where the opening δ is 180 degrees as shown in fig. 2, the radiation oscillator 130 has a semi-elliptical plate shape, and the plate surface is arranged perpendicular to the floor 110 with the expanding direction set to the rear direction (the Y-axis negative direction). The plate surface may be disposed parallel to the XZ plane. In fig. 2, the center line of the radiation oscillator 130 in the left-right direction is indicated by a one-dot chain line.

Here, basic characteristics of the antenna 100, particularly characteristics determined based on a self-similar shape, will be described. For ease of understanding, a bow tie antenna, which is well known as a self-similar shaped antenna, is illustrated. First, as a premise, when the antenna size and the frequency are in an inversely proportional relationship, the electrical characteristics of the antenna represent the same characteristics in principle even if the antenna size or the frequency is changed. For example, in the case of a monopole antenna, when the current distribution shows a resonant Behavior (Behavior), the antenna size (height) L and the frequency f are expressed by the relational expression (1) shown in fig. 3. In general, behavior of frequency f at a certain antenna size L is the same as behavior of frequency nf at antenna size L/n of 1/n shown in relational expression (2).

Next, as shown in fig. 4, a structure in which two isosceles triangle-shaped radiation oscillators having infinite heights are arranged to face each other with their apexes opposed to each other is considered. The antenna of this configuration is a bow tie antenna. In this configuration, the shape is the same and has a self-similar relationship before and after the change regardless of the change in the scale (size) (1/n times in the example of fig. 4). Therefore, regardless of how many times the frequency is, both of them show the same electrical characteristics when the antenna size is the same. In particular, the output impedance has a substantially constant value at any frequency, and thus is an important characteristic in a broadband antenna.

Since the size of an antenna that can be realistically fabricated is limited, a limited range of self-similar shapes is truncated for use. For example, as shown by the broken line in fig. 5, when the vertex is cut at a position having a predetermined length from the vertex with respect to the vertex to be butted, a constant characteristic independent of the frequency is expressed only at or above a predetermined frequency determined by the length from the vertex after the cut. The lower limit of the frequency showing this characteristic has an inversely proportional relationship with the antenna size.

In addition, in actual design, the shape of the radiation oscillator may be modified from an isosceles triangle for adjustment of impedance and the like. For example, the isosceles triangle shape can be designed to be a semi-elliptical shape like the radiation element 130 of the antenna 100 of the present embodiment. In this case, fixed electrical characteristics obtained from the self-similar shape can also be utilized.

The antenna 100 of the present embodiment includes a floor 110 and one radiation element 130 having a self-similar shape, instead of a structure in which two radiation elements are disposed so that their apexes face each other, as in a bow tie antenna. The end 135 that is the standard of the similar shape is arranged in a state of being raised toward the floor panel 110. With this configuration, the antenna 100 of the present embodiment can similarly obtain substantially the same operational effects as the bow tie antenna. Although there is only one radiation element 130, the floor 110 can obtain an operational effect that another radiation element is virtually disposed on the opposite side.

Returning to fig. 2. The radiation oscillator 130 having the self-similar shape (for example, a half-elliptical shape) as described above has the expanded shape of the radiation oscillator 130 formed by the 1 st radiation element section 131 and the 2 nd radiation element section 133 that are plane-symmetric with respect to a predetermined virtual plane of symmetry (a plane parallel to the YZ plane in the example of fig. 2) a1 in the expansion direction (a rear direction that is a negative direction of the Y axis in the example of fig. 2). In the present embodiment, the 1 st radiation element section 131 and the 2 nd radiation element section 133 are integrally configured by a straight line portion along the center line on the virtual symmetry plane a1 as a bent portion 137 by the bent portion 137. In the radiation oscillator 130, the angle formed between the end 135 and the 1 st radiation element part 131 is acute, and the angle formed between the end 135 and the 2 nd radiation element part 133 is acute. The end 135 is disposed on the floor 110. Thus, the angle formed by the end 135 and the 1 st radiation oscillator unit 131 corresponds to the angle formed by the portion of the 1 st radiation oscillator unit 131 outside the end 135 and the floor panel 110. Similarly, the angle formed by the end 135 and the 2 nd radiating element section 133 corresponds to the angle formed by the portion of the 2 nd radiating element section 133 outside the end 135 and the floor panel 110. The angle formed by the end 135 and the 1 st radiation element section 131 is substantially the same as the angle formed by the end 135 and the 2 nd radiation element section 133.

In the radiation element 130, the opening degree (angle formed by the 1 st radiation element section 131 and the 2 nd radiation element section 133) δ of the radiation element 130 is set by the bending angle of the bending section 137. Fig. 6 shows an antenna 100 having an opening δ of 60 degrees. The antenna 100 can change its characteristics by changing the opening δ.

Fig. 7 is a plan view of antenna 100 in a case where an angle formed by 1 st radiating element section 131 and 2 nd radiating element section 133, that is, an opening δ is 180 degrees. In addition, the bending angle θ is also shown as a displacement angle of each of the 1 st radiation element unit 131 and the 2 nd radiation element unit 133 after the 1 st radiation element unit 131 and the 2 nd radiation element unit 133 are bent at the bending portion 137 in a state where the 1 st radiation element unit 131 and the 2 nd radiation element unit 133 are made to be the same plane. In the case of fig. 7, the bending angle θ is 0 degree. The angle can be converted by δ 180- θ × 2. Fig. 8 is a plan view of the antenna 100 when δ is 120 degrees (θ is 30 degrees), fig. 9 is a plan view of the antenna 100 when δ is 90 degrees (θ is 45 degrees), fig. 10 is a plan view of the antenna 100 when δ is 60 degrees (θ is 60 degrees), and fig. 11 is a plan view of the antenna 100 when δ is 20 degrees (θ is 80 degrees). As is apparent from fig. 8 to 11, the expanded shapes of the 1 st radiation element portion 131 and the 2 nd radiation element portion 133 are V-shaped (mountain-shaped) shapes obtained by bending the 1 st radiation element portion 131 and the 2 nd radiation element portion 133 at the bending portion 137 in a plan view. Fig. 12 to 17 are diagrams showing directivity patterns of horizontal planes (XY planes) obtained by the bending angles θ of fig. 7 to 11 at different frequencies. Specifically, fig. 12 shows a directivity pattern when the use frequency is 1700MHz, fig. 13 shows a directivity pattern when the use frequency is 2500MHz, fig. 14 shows a directivity pattern when the use frequency is 3500MHz, fig. 15 shows a directivity pattern when the use frequency is 4500MHz, fig. 16 shows a directivity pattern when the use frequency is 5500MHz, and fig. 17 shows a directivity pattern when the use frequency is 6000 MHz.

For example, as shown in fig. 12, when the frequency of use is 1700MHz (═ 1.7GHz), there is no large difference in directivity in each azimuth, and even when the opening δ is changed from 180 degrees to 20 degrees (the bending angle θ is changed from 0 degrees to 80 degrees), no significant difference in directivity is exhibited at 1700 MHz. On the other hand, when the frequency is increased as shown in fig. 13 to 17, the directivity of each opening degree δ (bending angle θ) is different. For example, in 6000MHz (═ 6.0GHz) shown in fig. 17, a difference in directivity according to the degree of opening δ (bending angle θ) is clearly shown.

Specifically, when the opening degree δ is 180 degrees (the bending angle θ is 0 degrees), the gain in azimuth in the Y-axis positive direction (the forward direction, the azimuth 180 degrees direction) and the Y-axis negative direction (the backward direction, the azimuth 0 degrees direction) is equally high in comparison with the X-axis direction (the left-right direction) at 6.0GHz, and the directivity in the limited azimuth range of about 60 degrees (the sum of the azimuth 0 degrees to the azimuth 30 degrees and the azimuth 330 degrees to the azimuth 360 degrees in the case of the backward direction) is exhibited in each of the forward direction and the backward direction. On the other hand, when the opening δ is decreased from 180 degrees (the bending angle θ is increased from 0 degree), a higher gain is exhibited than when the opening δ is 180 degrees (the bending angle θ is 0 degree) in the azimuth of the rear direction (the Y-axis negative direction) which is the expanding direction. When the opening degree δ is decreased (the bending angle θ is increased), the azimuth angle range in which a high gain is exhibited gradually expands from the azimuth in the rear direction (Y-axis negative direction) as the expanding direction to the azimuth close to the left-right direction. Conversely, the gain on the front direction (Y-axis positive direction) side, which is opposite to the expansion direction, decreases as the opening δ decreases (the bending angle θ increases). In this way, the antenna 100 of the present embodiment has the following operational effects: that is, if the frequency becomes high, the directivity in the expansion direction is exhibited and the difference in the directivity corresponding to the opening δ is exhibited; when the opening degree δ is small (the bending angle θ is large), the azimuth angle range in which a high gain can be obtained is gradually enlarged centering on the azimuth in the expanding direction.

When the antenna band frequency of the antenna 100 includes 5 to 6GHz, a high gain can be obtained on the expansion direction side by setting the opening δ to a range of 1 degree or more and 179 degrees or less, but it is preferable that the opening δ is set to a range of 20 degrees or more and 160 degrees or less, and thus it can be said that an azimuth angle range in which a high gain can be obtained on the expansion direction side including the azimuth in the expansion direction can be obtained. At this time, even when the lower limit of the antenna band frequency is 1GHz and the use frequency is 1GHz, the gain is high in all azimuths as estimated from fig. 12, and the gain on the expansion direction side is kept high. Therefore, it can be said that configuring the antenna 100 with the opening δ in the range of 20 degrees or more and 160 degrees or less and setting the lower limit of the antenna band frequency to 1GHz or more are the antenna characteristics of the wide band practically used according to the band of the current and future mobile communication standards.

However, when the frequency exceeding 4GHz is set as the use frequency of the antenna 100 alone, a high gain in the expansion direction can be obtained by setting the opening δ to a range of 20 degrees or more and 160 degrees or less, and on the opposite side, for example, the gain in the direction opposite to the expansion direction becomes low. As a result, a plurality of individual antennas 100 can be arranged with their spreading directions oriented in different directions according to the characteristics exhibited by the individual antennas 100, thereby realizing a broadband antenna having high gain and no directivity or nearly no directivity as a whole. For example, in the antenna 100 shown in fig. 6 and the like, the other antennas 100 are arranged back to back with the spreading directions set to opposite directions (with the spreading direction of the radiation element 130 set to the positive Y-axis direction). The antenna device 10 of fig. 1 is configured as an example. This makes it possible to realize the antenna device 10 having nondirectivity or nearly nondirectivity as the whole antenna device having two antennas 100.

Fig. 18 is a diagram showing a characteristic of a pass loss of electric power from a feeding point of one antenna 100 to a feeding point of the other antenna 100 in a case where two antennas 100 having opposite spreading directions are arranged to constitute one antenna device. The values of the pass loss when the opening δ of each radiation transducer 130 is set to 180 degrees, 140 degrees, 120 degrees, 60 degrees, and 20 degrees (when represented by the bending angle θ, 0 degree, 20 degrees, 30 degrees, 60 degrees, and 80 degrees) respectively. As shown in fig. 18, when a plurality of antennas 100 are arranged, the value of the pass loss becomes lower as the opening δ becomes smaller (the bending angle θ becomes larger), and the isolation between the antennas 100 can be improved in a wide frequency range.

As described with reference to fig. 12 to 17, even with the same opening δ, the azimuth angle range in which high gain can be obtained at 6.0GHz is narrower than 1.7 GHz. Further, by reducing the opening δ, the azimuth angle range in which high gain can be obtained around the expansion direction can be expanded. The reduction of the opening δ also relates to an increase in the isolation as shown in fig. 18. However, when the opening δ is reduced, the gain in the azimuth direction (the Y-axis negative direction) of the expanding direction is gradually reduced. Therefore, when the antenna device is configured by a plurality of antennas 100, by appropriately selecting the opening δ (bending angle θ) of each antenna 100 to be used, the balance between the gain, the range of directivity, and the isolation can be optimized.

Fig. 19 is a diagram showing electrical characteristics of the antenna 100. The vswr (voltage standard Wave ratio) of the antenna 100 when the opening δ is set to 180 degrees, 140 degrees, 120 degrees, 60 degrees, and 20 degrees (0 degrees, 20 degrees, 30 degrees, 60 degrees, and 80 degrees when represented by the bending angle θ). As shown in fig. 19, the antenna 100 does not have a fixed opening δ showing an optimal VSWR in the entire frequency range of 1.7GHz to 6.0 GHz. However, it can be said that, in the case where the opening δ is approximately 60 to 140 degrees, a more favorable VSWR can be obtained in the entire frequency range of 1.7GHz to 6.0GHz than in the case of the other openings δ. In addition, in the frequency range of 4.7GHz to 5.4GHz, the VSWR characteristic is optimal when the opening δ is 20 degrees. Therefore, referring to the characteristics of fig. 12 to 17 and 19, by appropriately selecting the opening δ (bending angle θ) of the antenna 100 to be used, the balance between the gain, the range of directivity, and the VSWR can be optimized.

In order to reduce the size of the in-vehicle antenna device 1 and to accommodate more antennas in the in-vehicle antenna device 1, the size of the antenna 100 is desirably as small as possible, but a certain degree of size is required to obtain desired antenna characteristics. Therefore, in the antenna 100 of the present embodiment, the height of the radiation element 130 is set to be equal to or greater than 1/8 wavelengths of the radio wave at the lower limit of the antenna band frequency. The height of the radiating element 130 is defined as follows. The length of the radiation element 130 along the direction of the zigzag line of the zigzag portion 137 when the radiation element 130 is viewed as being projected onto the virtual symmetry plane a1 is defined as the height of the radiation element 130. The radiation element 130 has a shape that is bent at the bent portion 137. In the case of the antenna 100 in which the opening δ is set to 180 degrees without bending, the mode shown in fig. 2 is used. At this time, when the radiation transducer 130 is observed as being projected onto the virtual symmetry plane a1, the image of the projection is a zigzag line (center line indicated by a one-dot chain line in fig. 2) as the zigzag portion 137, and the length along the direction of the zigzag line is the length of the zigzag line itself. Therefore, with respect to the radiating element 130 of fig. 2, the length of the broken line is the height of the radiating element 130.

In the case of the antenna 100 in which the opening δ is set to 60 degrees as shown in fig. 6, when the radiation element 130 is projected and observed on the virtual symmetry plane a1 (see fig. 2), the image in the projection observation is an image in a shape in which an ellipse is quartered by the major axis and the minor axis. However, in this case, the length of the bent portion 137 along the bent line also becomes the length of the bent line. Thus, the length of the meander line becomes the height of the radiation oscillator 130.

In fig. 2 and 6, the antenna 100 is set in an upright state in which the meander line of the meander 137 is perpendicular to the floor 110, but the height of the radiating element 130 is defined in the same manner even when the antenna is set in an upright state in which the meander line of the meander 137 is not upright and the spreading direction is inclined upward. Even when the radiation element 130 having the opening δ of 180 degrees is not formed in a semi-elliptical shape (for example, in the shape of fig. 20 described later), the height of the radiation element 130 is defined in the same manner. The height of the radiation element 130 can be set to be equal to or greater than 1/8 wavelengths of the lower limit radio wave of the antenna band frequency.

As described above, according to the antenna 100 of the present embodiment, the gain in the spreading direction can be increased. Therefore, the directivity of the antenna 100 can be controlled according to the orientation of the radiation element 130 disposed on the floor 110 (to which orientation the spreading direction is disposed), and a broadband antenna in which the gain in a desired direction is improved can be realized.

In addition, according to the antenna device 10 having a plurality of (for example, two) antennas 100, the gain in the spreading direction can be increased by each antenna 100. Therefore, by adjusting the number of antennas 100, the respective spreading directions, and/or the opening δ thereof so as to cover all the azimuths, it is possible to realize an antenna device having a high gain and no directivity (or a characteristic close to no directivity) in a wide band.

Each antenna 100 constituting the antenna device 10 is disposed at a position lower than the broadcast antenna 20, which is another antenna. In addition, the antenna band frequency of the other antenna (in this case, the broadcast antenna 20) is lower than the antenna band frequency (1GHz or more) of the antenna 100. Therefore, it can be said that the interference with the antenna 100 from another antenna (in this case, the broadcast antenna 20) is difficult.

The height of the radiation element 130 is equal to or greater than 1/8. Therefore, when the antenna band frequency is 1GHz or more, the height can be reduced in particular, and the degree of freedom of arrangement in the in-vehicle antenna device 1 can be improved.

The above describes an example of the embodiment. The embodiment to which the present invention can be applied is not limited to the above-described embodiments, and addition, omission, and change of the constituent elements can be appropriately performed. For example, the present invention can be applied to the following modified examples of the above-described embodiments.

[ modification 1]

For example, in the above-described embodiment, the radiation oscillator 130 having a half-elliptical shape with the opening δ of 180 degrees is exemplified, but the shape of the radiation oscillator is not limited thereto, and an isosceles triangle shape or a shape obtained by appropriately designing and modifying the shape can be adopted. In this case, the angle formed by the end portion and the 1 st radiation element portion is also an acute angle, and the angle formed by the end portion and the 2 nd radiation element portion is also an acute angle. The angle formed by the end portion and the 1 st radiation oscillator unit is substantially the same as the angle formed by the end portion and the 2 nd radiation oscillator unit.

Further, the shape as shown in fig. 20 may be adopted. Fig. 20 is a diagram showing an example of the structure of the antenna 100b according to the present modification. As shown in fig. 20, radiation element 130b constituting antenna 100b according to the present modification has a shape obtained by cutting out a part of radiation element 130 shown in fig. 6. Specifically, the radiation element 130b has a shape in which a central portion (a portion indicated by a broken line in fig. 20) including the bent portion 137 is cut out from the radiation element 130 shown in fig. 2 and 6.

In the above-described embodiment, as described with reference to fig. 8 to 11, the spread shape determined based on the 1 st radiation element unit 131 and the 2 nd radiation element unit 133 is a V-shape (mountain shape) in which the 1 st radiation element unit 131 and the 2 nd radiation element unit 133 are bent at the bent portion 137 in a plan view. In this modification, the approximate shape is also almost the same. The two radiating element sections (the 1 st radiating element section 131b and the 2 nd radiating element section 133b) included in the antenna 100b are arranged in a V-shape (mountain-shape) with the end section 135 as a base point in a plan view. Thus, when the 1 st radiation element unit 131b and the 2 nd radiation element unit 133b are projected toward the end portion 135 side in a plan view, the expanded shape is a V-shape (mountain shape) with the end portion 135 as a base point. Similarly to the radiation element 130, the radiation element 130b has a spread shape of the radiation element 130b, which is formed by the 1 st radiation element section 131b and the 2 nd radiation element section 133b that are plane-symmetric with respect to the virtual plane of symmetry a 2.

In the radiation element 130b, a linear portion along a center line on the virtual symmetry plane a2 is defined as a virtual bend 137 b. The virtual bend 137b is a portion extending from the 1 st radiation element 131b and the 2 nd radiation element 133b toward the virtual symmetry plane a2, and is a linear portion intersecting the virtual symmetry plane a 2. That is, the 1 st radiation element unit 131b and the 2 nd radiation element unit 133b are integrally configured so as not to include a part of the predetermined virtual bend 137b located on the virtual symmetry plane a 2. In the radiation element 130b, the angle formed between the end 135 and the 1 st radiation element part 131b is an acute angle, and the angle formed between the end 135 and the 2 nd radiation element part 133b is an acute angle. The end 135 is disposed on the floor 110. Thus, the angle formed by the end 135 and the 1 st radiation element part 131b corresponds to the angle formed by the portion of the 1 st radiation element part 131b outside the end 135 and the floor panel 110. Similarly, the angle formed by the end 135 and the 2 nd radiating element section 133b corresponds to the angle formed by the portion of the 2 nd radiating element section 132b outside the end 135 and the floor panel 110. The angle formed by the end 135 and the 1 st radiation element section 131b is substantially the same as the angle formed by the end 135 and the 2 nd radiation element section 133 b.

When the opening δ of the 1 st radiation element unit 131b and the 2 nd radiation element unit 133b is set to 180 degrees as in the case of the radiation element 100 of fig. 2, when the radiation element 130b is projected and observed on the virtual symmetry plane a2, an image obtained by the projection and observation is a virtual zigzag line as the virtual zigzag portion 137 b. In the radiation element 130b having the opening δ of 180 degrees, the length of the radiation element 130b in the direction along the virtual zigzag line direction is the length of the virtual zigzag line itself. Therefore, at an arbitrary opening δ, the length of the virtual zigzag line of the radiation transducer 130b becomes the height of the radiation transducer 130 b. In the antenna 100b according to the modification of the present embodiment, the height of the radiating element 130b is set to be equal to or greater than the 1/8 wavelength of the radio wave at the lower limit of the antenna band frequency.

When the frequency of the antenna 100b having such a partially cut-out shape is increased, the directivity at each opening δ (bending angle θ) is different as in the case shown in fig. 12 to 17.

More specifically, fig. 27 shows a directivity pattern when the use frequency is 1700MHz, fig. 28 shows a directivity pattern when the use frequency is 2500MHz, fig. 29 shows a directivity pattern when the use frequency is 3500MHz, fig. 30 shows a directivity pattern when the use frequency is 4500MHz, fig. 31 shows a directivity pattern when the use frequency is 5500MHz, and fig. 32 shows a directivity pattern when the use frequency is 6000 MHz.

For example, as shown in fig. 27, when the frequency of use is 1700MHz (═ 1.7GHz), there is no large difference in directivity in each azimuth, and even when the opening δ is changed from 180 degrees to 20 degrees (the bending angle θ is changed from 0 degrees to 80 degrees), no significant difference in directivity is exhibited at 1700 MHz. On the other hand, when the frequency is increased as shown in fig. 28 to 32, the directivity of each opening degree δ (bending angle θ) is different. For example, in 6000MHz (═ 6.0GHz) shown in fig. 32, a difference in directivity according to the opening δ (bending angle θ) is clearly shown. Fig. 27 to 32 are diagrams showing directivity patterns of horizontal planes (XY planes) at different frequencies at respective bending angles θ.

In addition, an antenna device including a plurality of antennas 100b according to the present modification can be configured. For example, as shown in fig. 21, an antenna device 10b can be configured in which two antennas 100b-1 and 100b-2 are disposed while sharing a floor 110. Specifically, the radiation elements 130b of the antennas 100b-1 and 100b-2 are disposed on the floor 110 so that the directions of expansion are different from each other (in the example of fig. 21, the directions are opposite to each other in the front-rear direction along the Y axis direction). According to the antenna device 10b, the correlation coefficient between the radiation elements 130b can be reduced while maintaining the radiation efficiency of the radiation elements 130 b. Therefore, the isolation between the radiation oscillators 130b can be further improved.

Hereinafter, the electrical characteristics obtained by the antenna device 10b will be specifically described with reference to fig. 22 to 26. In fig. 22 to 26, two antennas are arranged as in the antenna device 10b shown in fig. 21. That is, in the antenna device 10b, the radiation elements 130b of the antennas having the same opening degree are arranged in different directions (for example, in the directions opposite to each other in the front-rear direction along the Y-axis direction) from each other in the opening direction. In fig. 22 to 26, an antenna device in which two antennas having no cutout are arranged is shown as a reference example. That is, in the antenna device of the reference example, as shown in fig. 6, the antenna elements having no cutout are arranged in different directions (for example, in opposite front-back directions along the Y-axis direction) from each other in the spreading direction. Note that the opening degree of each antenna in the antenna device of the reference example is the same as the opening degree of each antenna in the antenna device 10 b. In fig. 22 to 26, the opening degree δ is set to 20 degrees (the bending angle θ is 80 degrees).

Fig. 22 is a graph showing envelope correlation coefficients. The envelope correlation coefficient indicates the degree of similarity of the radiation patterns between the two antennas. Thus, the more similar the radiation patterns between the two antennas, the higher the envelope correlation coefficient. Hereinafter, the envelope correlation coefficient is appropriately referred to as a correlation coefficient. In the antenna device of the reference example, the correlation coefficient tends to be high in a frequency band ranging from 4000MHz (═ 4.0GHz) to a low band, and the correlation coefficient at 1700MHz (═ 1.7GHz) is about 0.6. This is presumably because, as shown in fig. 12, even if the opening degree δ is changed at 1700MHz, the directivity does not change significantly, and the radiation patterns are similar even if the two antennas are arranged in the front-rear opposite directions. On the other hand, in the antenna device 10b, the correlation coefficient tends to be high in the band ranging from 4000MHz to the low band, but the correlation coefficient at 1700MHz is about 0.4. That is, the antenna device 10b can reduce the increase in the correlation coefficient as compared with the antenna device of the reference example. In other words, in a frequency band in which the degree of change in directivity due to bending is small, the correlation coefficient varies depending on the presence or absence of a cut.

Fig. 23 is a diagram showing a characteristic of a pass loss of power from a feeding point of one antenna to a feeding point of another antenna. As shown in fig. 23, the antenna device of the reference example can improve the isolation between the antennas in a wide frequency range. In the antenna device 10b, the isolation can be further improved in a frequency band of 4000MHz or less (4.0 GHz or less), for example, as compared with the antenna device of the reference example.

Fig. 24 is a graph showing the horizontal plane average gain, fig. 25 is a graph showing the radiation efficiency, and fig. 26 is a graph showing the VSWR characteristic. As shown in fig. 24 to 26, the antenna device 10b has the same horizontal plane average gain, radiation efficiency, and VSWR characteristics as the antenna device of the reference example. That is, when the antenna elements having the same opening degree are arranged in different directions in the opening direction, the increase in the envelope correlation coefficient can be reduced and the isolation can be improved by having a shape in which a part of the antenna elements is cut out so that the horizontal plane average gain, the radiation efficiency, and the VSWR characteristics are hardly changed.

In the antenna device 10b, the two antennas 100b-1 and 100b-2 may be provided with a floor for each antenna without sharing the floor 110. In the antenna device 10, the two antennas 100-1 and 100-2 may be provided on different floors (specifically, a ground wiring of a substrate, a metal chassis, a roof of a vehicle, and the like) without sharing the floor 110, as in the configuration of the above embodiment.

[ other modifications ]

In the above-described embodiment, the antenna device 10 having two antennas 100 is exemplified, but the number of antennas 100 constituting the antenna device 10 is not limited to two, and three or more antennas 100 may be provided. For example, the number of antennas 100 may be four, and the respective radiating elements 130 may be arranged so that the expanding directions thereof are oriented in four directions, i.e., front, rear, left, and right directions.

The opening δ of each of the plurality of antennas 100 included in the antenna device 10 does not need to be the same, and may be different angles. Since the gain of the antenna 100 at a lower frequency is increased for a higher height, the height of the antenna 100 may be adjusted to a different height in order to increase the gain in the frequency band or bands used.

In the above-described embodiment, when a plurality of antennas 100 are arranged, the radiation elements 130 are arranged so that the directions of expansion thereof are different from each other. On the other hand, the radiation elements 130 may be arranged so that the spreading directions thereof are the same. This can increase the gain in the direction in which the radiation oscillator 130 is oriented. In this case, the opening δ of each radiation transducer 130 may be changed.

In the above-described embodiment, the configuration in which the plurality of antennas 100 are arranged behind the broadcast antenna 20 as shown in fig. 1 in the in-vehicle antenna device 1 has been described, but the embodiment is not limited to this. For example, in the in-vehicle antenna device 1, the arrangement of the plurality of antennas 100 can be arbitrarily changed. For example, the plurality of antennas 100 may be arranged in front of the broadcast antenna 20. In addition, for example, the plurality of antennas 100 may be arranged in a positional relationship sandwiching the broadcast antenna 20. For example, the plurality of antennas 100 may be arranged in a positional relationship sandwiching the broadcast antenna 20 from the front and rear direction, or may be arranged in a positional relationship sandwiching the broadcast antenna 20 from the left and right direction.

In the in-vehicle antenna device 1, when one or more antennas 100 are disposed in front of or behind the broadcast antenna 20, at least a part of the one or more antennas 100 may be disposed in a region substantially on the center line in the front-rear direction of the capacitive load element 23. In the in-vehicle antenna device 1, when the plurality of antennas 100 are arranged in a positional relationship with the broadcast antenna sandwiched therebetween from the front and rear directions, at least a partial region of one or more antennas 100 may be arranged on a substantially central line in the front and rear directions of the capacitive load element 23.

In addition, in the case of operating in a frequency band on the high-band side, the height of the antenna 100 can be designed to be lower. As a result, the degree of freedom in designing the antenna 100 can be improved.

In the above-described embodiment, the configuration in which the antenna 100 is housed in the antenna case 11 has been described, but the antenna may be housed in a case other than the antenna case 11. In other words, the antenna 100 may be housed in a casing other than the shark fin-shaped antenna casing 11. In this case, the shape of the case can be arbitrarily changed.

In the above-described embodiment, the in-vehicle antenna device mounted on the vehicle is exemplified, but the invention is not limited thereto. For example, the present invention can be applied to an antenna device mounted on an aircraft, a ship, or the like, an antenna device used in a base station for wireless communication, or the like.

Description of the reference numerals

1 … vehicle-mounted antenna device

11 … antenna casing

13 … antenna base

10 … antenna device

100(100-1, 100-2), 100b (100b-1, 100b-2) … antenna

110 … floor

130, 130b … radiating element

131 … 1 st radiation element part

133 … 2 nd radiation oscillator unit

135 … end part

137 … bend

151 … feeder line (feed)

20 … broadcast antenna

30 … satellite broadcasting antenna

40 … GNSS antenna

Delta … opening degree

Theta … angle of flex