Antenna equipment, dipole antennas, and vehicles

Abstract

Provided is an antenna device comprising: a signal line-side conductor; a ground-side conductor; and an antenna element to which the signal line-side conductor is electrically connected. At least the antenna element and a conductor frame, of a vehicle, to which the ground-side conductor is electrically connected constitute a dipole antenna. Further provided is a dipole antenna comprising: a signal line-side antenna element to which a signal line-side conductor is electrically connected; and a ground-side antenna element which is at least a conductor frame of a vehicle and to which a ground-side conductor is electrically connected. Still further provided is a vehicle comprising a conductor frame and an antenna device. The antenna device includes a signal line-side conductor, a ground-side conductor, and an antenna element to which the signal line-side conductor is electrically connected. The antenna element and the conductor frame to which the ground-side conductor is electrically connected constitute a dipole antenna.

Description

Technical Field

[0001] The present invention relates to an antenna device, a dipole antenna, and a vehicle.

Background Art

[0002] Patent Document 1 describes an antenna device in which an antenna element is installed in a spoiler of a vehicle.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the antenna device of Patent Document 1, in order to operate as a monopole antenna, a large conductor surface (for example, the roof of a vehicle) is required as a ground. Also, it is necessary to install the antenna element as far as possible from other conductors (for example, the body of a vehicle). That is, when installing the antenna device on a vehicle, it has been difficult to freely layout the antenna device due to restrictions such as electrical performance and installation location.

[0005] An example of the object of the present invention is to improve the freedom of layout of the antenna device in a vehicle. Other objects of the present invention will become apparent from the description herein.

Means for Solving the Problems

[0006] One aspect of the present invention includes a signal - line - side conductor, a ground - side conductor, and an antenna element to which the signal - line - side conductor is electrically connected, and at least the antenna element and a conductor frame of a vehicle to which the ground - side conductor is electrically connected form a dipole antenna, and it is an antenna device.

[0007] One aspect of the present invention is a dipole antenna comprising a signal line side antenna element to which a signal line side conductor is electrically connected, and a ground side antenna element which is at least a vehicle conductor frame to which a ground side conductor is electrically connected.

[0008] One aspect of the present invention is a vehicle comprising a conductor frame and an antenna device, wherein the antenna device has a signal line side conductor, a ground side conductor, and an antenna element to which the signal line side conductor is electrically connected, and the antenna element and the conductor frame to which the ground side conductor is electrically connected form a dipole antenna.

[0009] According to the above-described embodiment of the present invention, the degree of freedom in the layout of the antenna device in a vehicle can be improved. [Brief explanation of the drawing]

[0010] [Figure 1] This is a perspective view of a vehicle 1 on which the antenna device 10 of this embodiment is installed. [Figure 2] This is an exploded perspective view of the antenna device 10 of this embodiment. [Figure 3] This is an explanatory diagram illustrating the general configuration of how the outer conductor 182 of the coaxial cable 18 is electrically connected to the conductor frame 2 of the vehicle 1. [Figure 4] This is an explanatory diagram showing in detail how the outer conductor 182 of the coaxial cable 18 is electrically connected to the conductor frame 2 of the vehicle 1. [Figure 5] This figure shows an example of the frequency characteristics of the gain in the vertical polarization component of a dipole antenna 20. [Figure 6] This figure shows an example of the frequency characteristics of the gain in the horizontal polarization component of a dipole antenna 20. [Figure 7] This figure shows an example of the average gain of the antenna device 10 at different installation locations. [Figure 8] This is an explanatory diagram of modified antenna devices 10A and dipole antenna 20A. [Modes for carrying out the invention]

[0011] The following matters become clear from this specification and the accompanying drawings:

[0012] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. The same or equivalent components, members, etc. shown in each drawing are denoted by the same reference numerals, and redundant explanations will be omitted as appropriate.

[0013] =!!!Execution!!!!!! Figure 1 is a perspective view of a vehicle 1 on which the antenna device 10 of this embodiment is installed.

[0014] <<Definition of direction, etc.>> First, with reference to Figure 1, we define the direction and other parameters of the antenna device 10 in this embodiment.

[0015] As shown in Figure 1, the direction forward as viewed from the driver's seat of the vehicle 1 on which the antenna device 10 is installed is defined as the +X direction (forward direction) of the antenna device 10, the direction left as viewed from the driver's seat of the vehicle 1 is defined as the +Y direction (left direction) of the antenna device 10, and the direction upward as viewed from the driver's seat of the vehicle 1 is defined as the +Z direction (upward direction) of the antenna device 10. The opposite directions of the +X, +Y, and +Z directions are defined as the -X direction (rearward direction), the -Y direction (right direction), and the -Z direction (downward direction), respectively.

[0016] The +X, -X, +Y, -Y, +Z, and -Z directions are all unidirectional (directions with a fixed orientation). Furthermore, sometimes both directions, such as +X and -X, are simply referred to as the "X direction." Similarly, both directions, such as +Y and -Y, are simply referred to as the "Y direction." Also, both directions, such as +Z and -Z, are simply referred to as the "Z direction."

[0017] In FIG. 1, in order to facilitate the understanding of the directions and the like in the antenna device 10, the directions of the +X direction, +Y direction, and +Z direction are each represented by a line segment with an arrow. Note that the intersection of these line segments with arrows does not mean the coordinate origin.

[0018] Unless otherwise specified, the definitions of the directions and the like described above are common to other embodiments of this specification.

[0019] <<Overview of Antenna Device 10>> Next, while referring to FIG. 1 described above again, the overview of the antenna device 10 of this embodiment will be described.

[0020] As shown in FIG. 1, the antenna device 10 is an antenna device installed in the vehicle 1. The vehicle body of the vehicle 1 has a frame (hereinafter sometimes referred to as "conductor frame 2") formed of a conductor (for example, metal) as a structure. Examples of the conductor frame 2 in the side portion of the vehicle body include an A pillar (front pillar) 2A, a B pillar (center pillar) 2B, and a C pillar (rear pillar) 2C. Examples of the conductor frame 2 in the ceiling portion of the vehicle body include a front roof 2D, a center roof reinforcement 2E, a rear roof 2F, and a side roof 2G.

[0021] In the conductor frame 2 of the vehicle 1 exemplified above, conductor portions extending in a predetermined direction are combined to form a lattice structure. Specifically, the conductor frame 2 has a lattice structure formed by a conductor portion extending in the vertical direction (here, the Z direction) and a conductor portion extending in the horizontal direction (a direction perpendicular to the Z direction here). In the following description, the conductor portion extending in the vertical direction (Z direction) may be referred to as the "first conductor portion", and the conductor portion extending in the horizontal direction (a direction perpendicular to the Z direction) may be referred to as the "second conductor portion". However, the direction in which the first conductor portion extends does not have to be a strictly vertical direction, and it may be a direction having a predetermined angle of 0 degrees or more with respect to at least the horizontal plane (a direction rising at a predetermined angle). Similarly, the direction in which the second conductor portion extends does not have to be a strictly horizontal direction, and it is sufficient that the angle with respect to the horizontal plane is smaller than the angle of the first conductor portion with respect to the horizontal plane (the predetermined angle described above).

[0022] In the conductor frame 2 of the vehicle 1 illustrated above, as shown in Figure 3, the A-pillar 2A, B-pillar 2B, and C-pillar 2C correspond to the first conductor portion, and the front roof 2D, center reinforcement 2E, rear roof 2F, and side roof 2G correspond to the second conductor portion. The antenna device 10 of this embodiment is installed at the intersection of the first conductor portion and the second conductor portion, specifically at the intersection 3 between the B-pillar 2B and the center reinforcement 2E. However, the antenna device 10 may also be installed at a predetermined location on the conductor frame 2 other than the intersection 3 shown in Figure 1, such as the intersection of the A-pillar 2A and the front roof 2D.

[0023] Furthermore, the antenna device 10 may be installed in various locations other than the conductor frame 2 of the vehicle 1, as long as the ground-side conductor 32, described later, is electrically connected to the conductor frame 2. For example, the antenna device 10 may be installed on the roof panel, windshield, rear window, glass roof, side mirrors, inside the instrument panel, the top of the dashboard, the overhead console, the bumper, the license plate mounting area, the spoiler, etc. of the vehicle 1. In this way, the antenna device 10 can be freely laid out in various locations on the vehicle.

[0024] As shown in Figure 1, the antenna device 10 of this embodiment is positioned along the back surface of the conductor frame 2 (specifically, the center reinforcement 2E) of the vehicle 1, and is positioned so that the antenna device 10 and the conductor frame 2 overlap when viewed from outside the conductor frame 2. In this embodiment, even when the antenna device 10 is positioned so that it overlaps with the conductor frame 2, the effects of deterioration in gain and other factors can be minimized, as will be described later. Furthermore, the deterioration of the aesthetic appearance of the vehicle 1 due to the antenna device 10 being visible from the outside can be suppressed. However, the antenna device 10 does not have to be positioned so that the entire antenna device 10 and the conductor frame 2 overlap when viewed from outside the conductor frame 2. The antenna device 10 may be positioned so that a part of the antenna device 10 and the conductor frame 2 overlap, or the antenna device 10 and the conductor frame 2 may be positioned so that they do not overlap.

[0025] In this example, the vehicle 1 shown in Figure 1 is equipped with one antenna device 10. However, the vehicle 1 is not limited to having only one antenna device 10; multiple antenna devices 10 may be installed on the vehicle 1. Furthermore, the multiple antenna devices 10 installed on the vehicle 1 may support diversity communication methods or MIMO (Multiple-Input Multiple-Output) communication. In addition, the antenna device 10 may be arranged in the same enclosure in combination with other antennas (monopole antennas or planar antennas). In that case, it may be installed on the vehicle 1 as a system unit consisting of multiple antennas.

[0026] The configurations in which the antenna device 10 is installed on the vehicle 1 are not limited to the configuration in which it is attached to the vehicle 1, but also include the configuration in which it is brought into the vehicle 1 and used within the vehicle 1. Furthermore, "vehicle" means a vehicle with wheels, and examples include ordinary automobiles such as passenger cars, buses, and trucks, motorcycles and other two-wheeled vehicles, and special vehicles (industrial vehicles) such as tractors, bulldozers, and other specialized vehicles.

[0027] The antenna device 10 of this embodiment is compatible with radio broadcasts, for example, radio waves in the frequency band for AM / FM radio. That is, the antenna device 10 is compatible with both radio waves in the frequency band for AM broadcasting from 522kHz to 1710kHz and radio waves in the frequency band for FM broadcasting from 76MHz to 108MHz. However, the antenna device 10 may be compatible with only one of the frequency bands, either the AM broadcasting frequency band or the FM broadcasting frequency band.

[0028] The communication standards and frequency bands supported by the antenna device 10 are not limited to those described above, and other communication standards may also be supported. For example, the antenna device 10 may support radio waves in frequency bands for TEL (Telephone Communication), telematics, V2X (Vehicle to Everything: vehicle-to-vehicle communication, vehicle-to-infrastructure communication), such as 4G, 5G, and LTE. Furthermore, the antenna device 10 may support radio waves in frequency bands for GNSS (Global Navigation Satellite System), SXM (Sirius XM), ETC (Electronic Toll Collection system), Wi-Fi, Bluetooth, DAB (Digital Audio Networking), DTV (Digital Television Network), KEYLESS (Keyless Network System), etc.

[0029] <<Basic Configuration of Antenna Device 10>> Next, the basic configuration of the antenna device 10 of this embodiment will be described with reference to Figure 2.

[0030] Figure 2 is an exploded perspective view of the antenna device 10 of this embodiment.

[0031] The antenna device 10 includes a case 11A and a base 11B, a pad 12, a plate-shaped element 13, a bobbin 14, a helical element 15, a substrate 16, and cables 17A and 17B. Figure 2 shows an exploded perspective view of the antenna device 10 with only the case 11A moved in the +Z direction.

[0032] Case 11A and base 11B are components that constitute the exterior of the antenna device 10. Case 11A is located on the +Z side of the antenna device 10 and is formed in the shape of a plate. Similarly, base 11B is located on the -Z side of the antenna device 10 and is formed in the shape of a plate. The antenna device 10 is installed on the vehicle 1 by attaching base 11B to a predetermined location on the vehicle 1. However, the orientation in which the antenna device 10 is installed relative to the vehicle 1 is not limited to the orientation shown in Figure 2 (i.e., the orientation in which the antenna device 10 is installed with case 11A on the +Z side and base 11B on the -Z side), and may be any orientation.

[0033] Case 11A and base 11B are formed from an insulating resin such as PC resin, ASA resin, PC / ASA resin composition, or ABS resin. However, case 11A and base 11B may be formed from a material other than an insulating resin that transmits radio waves. Furthermore, case 11A and base 11B may consist of an insulating resin portion and a portion made of a material other than an insulating resin that transmits radio waves. In addition, parts of case 11A and base 11B may be made of a conductive material or a material that does not transmit radio waves. That is, case 11A and base 11B may be formed by freely combining desired materials, and case 11A and base 11B may be made of different materials.

[0034] The case 11A and the base 11B form a housing space for accommodating the plate-shaped element 13, bobbin 14, helical element 15, substrate 16, cable 17A, and cable 17B. The case 11A and the base 11B are attached to each other by desired mounting means such as screw fastening, snap fitting, welding, or adhesive.

[0035] The pad 12 is a component positioned between the case 11A and the base 11B. The pad 12 is compressed by being sandwiched between the case 11A and the base 11B, thereby ensuring the waterproofness of the housing space of the antenna device 10. The pad 12 is formed of an elastic material such as TPE or rubber (such as NBR or EPDM). However, the pad 12 may be formed of other elastic materials.

[0036] The plate-shaped element 13, together with the helical element 15, is an element that corresponds to radio waves in the frequency band for AM / FM radio. The plate-shaped element 13 is a capacitive element in an antenna for AM / FM radio, and is sometimes called a capacitively charged element. The -Y end of the plate-shaped element 13 is electrically connected to the +X end of the helical element 15. Here, "electrically connected" is not limited to physical (direct) connections, such as joining objects with a conductor such as solder, but also includes indirect connections, such as connecting via electronic circuits or electronic components. The same applies to the following explanation of "electrically connected".

[0037] In the antenna device 10 of this embodiment, the plate-shaped element 13 is built into the housing (i.e., the housing space formed by the case 11A and the base 11B), but the plate-shaped element 13 may be located outside the housing. Also, if the antenna device 10 does not support radio waves in the frequency band for AM broadcasting (for example, if it only supports radio waves in the frequency band for FM broadcasting), the plate-shaped element 13 may not be necessary. This makes it possible to miniaturize the antenna device 10.

[0038] The bobbin 14 is a member that supports the helical element 15. The helical element 15 is wound around the outer surface of the bobbin 14, except for both ends in the X direction. The bobbin 14 is made of an insulating resin such as PC resin, ASA resin, PC / ASA resin composition, or ABS resin. However, the bobbin 14 may be made of a material other than an insulating resin. However, the antenna device 10 does not have to have a bobbin 14. In this case, the helical element 15 may be supported on the substrate 16, or it may be supported on a support member made of a different resin than the bobbin 14.

[0039] The helical element 15, together with the plate-shaped element 13, is an element that corresponds to radio waves in the frequency band for AM / FM radio. However, the antenna device 10 does not have to have the helical element 15. In this case, only the plate-shaped element 13 is the element that corresponds to radio waves in the frequency band for AM / FM radio. The helical element 15 is an inductive element in an antenna for AM / FM radio and is sometimes called a helical element (or simply a "coil"). The +X end of the helical element 15 is electrically connected to the -Y end of the plate-shaped element 13, and the -X end of the helical element 15 is electrically connected to the substrate 16. As a result, the plate-shaped element 13, the helical element 15, and the substrate 16 are electrically connected in series.

[0040] The substrate 16 is a plate-shaped member on which conductor patterns and electronic components such as antenna impedance matching circuits and amplification circuits are arranged. In this embodiment, the substrate 16 is a printed circuit board (PCB), formed from a resin material such as glass epoxy resin, and on which conductor patterns and electronic components are arranged. However, the substrate 16 may be formed from a resin material other than glass epoxy resin, such as phenolic resin, and on which conductor patterns and electronic components are arranged.

[0041] Cable 17A is a cable having a conductor portion (hereinafter sometimes referred to as the "signal line side conductor") through which the signal of the antenna (in this case, the dipole antenna 20 described later) in the antenna device 10 is transmitted. Cable 17B is a cable having a conductor (hereinafter sometimes referred to as the "ground side conductor") that serves as the ground for the antenna (dipole antenna 20) in the antenna device 10. One end of cable 17A on the circuit board 16 side and the circuit board 16 are electrically connected to each other by a joint such as soldering. Similarly, one end of cable 17B on the circuit board 16 side and the circuit board 16 are electrically connected to each other by a joint such as soldering. Cables 17A and 17B are led outwards from the antenna device 10 via a grommet 19.

[0042] The antenna device 10 of this embodiment further includes a coaxial cable 18 (not shown in Figure 2; see Figures 3 and 4 described later). Outside the antenna device 10, cable 17A is electrically connected to the internal conductor 181 of the coaxial cable 18, and cable 17B is electrically connected to the external conductor 182 of the coaxial cable 18. Therefore, in the following description, both cable 17A and the internal conductor 181 of the coaxial cable 18 may be referred to as the "signal line side conductor," and both cable 17B and the external conductor 182 of the coaxial cable 18 may be referred to as the "ground side conductor."

[0043] However, the antenna device 10 does not have to have a coaxial cable 18, nor does it have to have cables 17A and 17B. In other words, the antenna device 10 does not have to be connected by cable. For example, a connector may be attached to the circuit board 16, and the antenna device 10 may be electrically connected to the outside of the antenna device 10 (in this case, the vehicle 1) via this connector. In this case, the circuit board 16 may have a conductor pattern that will be the signal line conductor and a ground pattern that will be the ground conductor. Also, if the antenna device 10 has a coaxial cable 19, the signal line conductor may be made up of the internal conductor 181 of the coaxial cable 18, and the ground conductor may be electrically connected directly from the circuit board 16 to the vehicle 1 with a metal terminal.

[0044] <<Overview of the Dipole Antenna 20>> Next, referring again to Figure 2, and then to Figures 3 and 4, we will describe the outline of the dipole antenna 20 configured in this embodiment.

[0045] Figure 3 is an explanatory diagram illustrating the general configuration of the electrical connection between the outer conductor 182 of the coaxial cable 18 and the conductor frame 2 of the vehicle 1. Figure 4 is an explanatory diagram illustrating the detailed configuration of the electrical connection between the outer conductor 182 of the coaxial cable 18 and the conductor frame 2 of the vehicle 1.

[0046] Incidentally, when a structure is required that the antenna device does not protrude from the vehicle's body, the antenna device needs to be particularly miniaturized. Also, when a glass roof or resin roof is used for the vehicle's roof, it may be difficult to use the roof as the ground for the antenna device. If the antenna in the antenna device is to operate as a monopole antenna, a large conductive surface such as the vehicle's roof is required, which limits the location where the antenna device can be laid out.

[0047] However, the antenna in the antenna device 10 of this embodiment operates as a dipole antenna. One element of the dipole antenna is an element inside the antenna device 10 (a plate-shaped element 13 and a helical element 15), and the other element of the dipole antenna is the conductor frame 2 of the vehicle 1.

[0048] In this embodiment, the elements (plate-shaped element 13 and helical element 15) inside the antenna device 10 to which the signal line-side conductor 31 (internal conductor 181 of the coaxial cable 18) is electrically connected become one of the elements of the dipole antenna 20 described above. In addition, at least a portion of the conductor frame 2 of the vehicle 1 to which the ground-side conductor 32 (external conductor 182 of the coaxial cable 18) is electrically connected becomes the other element of the dipole antenna 20 described above. As a result, in the antenna device 10 of this embodiment, the conductor frame 2 of the vehicle 1 can be used as part of the elements of the dipole antenna 20.

[0049] In the following explanation, the elements to which the signal line conductor 31 is electrically connected (here, the plate-shaped element 13 and the helical element 15) will be referred to as the "signal line antenna element," and the conductor frame 2 of the vehicle 1 to which the ground conductor 32 is electrically connected will be referred to as the "ground antenna element."

[0050] When a monopole antenna is placed close to the vehicle body, the current flowing through the antenna element of the monopole antenna is canceled out by the mirror effect with the vehicle body, resulting in a decrease in gain. However, in the antenna device 10 of this embodiment, by using a dipole antenna 20 made from the conductor frame 2 of the vehicle 1, it is possible to place it close to the vehicle body 1. Furthermore, since the conductor frame 2 acts as the opposite antenna of the dipole antenna 20, gain can be ensured. Therefore, in this embodiment, the degree of freedom in the layout of the antenna device 10 on the vehicle 1 can be improved.

[0051] Furthermore, it becomes possible to secure gain even if the antenna element on the antenna device 10 side (signal line side antenna element) is made smaller, allowing the antenna device 10 to be miniaturized. The antenna element on the antenna device 10 side (signal line side antenna element) is sufficiently small relative to the wavelength of the radio wave that the dipole antenna 20 corresponds to (for example, less than one-quarter of the wavelength), thereby ensuring sufficient distance from, for example, noise sources. In addition, the conductor frame 2 of the vehicle 1, which is the antenna on the opposite side of the dipole antenna 10, also functions as a ground by the vehicle body and has low impedance, making it less susceptible to noise. Therefore, the antenna device 10 can also suppress the effects of noise.

[0052] The length of the signal line side antenna element on the antenna device 10 side may be, for example, one-tenth or less of the actual length (physical length) of the ground side antenna element on the conductor frame 2 side. However, if the wavelength of the radio waves that the dipole antenna 20 corresponds to is shorter than the wavelength for AM / FM radio, such as the wavelength of radio waves for TEL, the length of the signal line side antenna element on the antenna device 10 side can be made sufficiently small, so the length of the signal line side antenna element on the antenna device 10 side does not need to be miniaturized to one-quarter of the wavelength of the radio waves that the dipole antenna 20 corresponds to.

[0053] As explained above, the conductor frame 2 of the vehicle 1 is used as the ground-side antenna element of the dipole antenna 20. However, this is not the only option; a portion of the outer conductor 182 of the coaxial cable 18 may also be used as the ground-side antenna element.

[0054] As shown in Figure 3, the outer conductor 182 of the coaxial cable 18 is electrically connected to the intersection 3 of the B pillar 2B, which is the first conductor portion extending vertically, and the center reinforcement 2E, which is the second conductor portion extending horizontally. In other words, the outer conductor 182 is electrically connected to both the first and second conductor portions. This allows more current to flow in the dipole antenna 20, thereby improving the gain. Furthermore, the dipole antenna 20 can handle both vertically and horizontally polarized signals. However, the outer conductor 182 only needs to be electrically connected to at least one of the ends of the first conductor portion on the second conductor portion side (hereinafter sometimes referred to as the "first end") and the ends of the second conductor portion on the first conductor portion side (hereinafter sometimes referred to as the "second end").

[0055] In this embodiment, the dipole antenna 20 is an antenna for linear polarization. This allows the dipole antenna 20 to improve the gain in both the vertical and horizontal components of the corresponding linear polarization. However, the dipole antenna 20 may be an antenna other than one for linear polarization.

[0056] Furthermore, as shown in Figure 3, the outer conductor 182 is electrically connected to at least one of its first end and second end on the side where the interior angle between the first axis X1 and the second axis X2 is located at the point where the first axis X1, which is along the direction in which the first conductor portion, the B pillar 2B, extends, and the second axis X2, which is along the direction in which the second conductor portion, the center reinforcement 2E, extends, intersects. This further improves the gain. However, the outer conductor 182 may also be electrically connected to at least one of its first end and second end on a side other than the side where the interior angle between the first axis X1 and the second axis X2 is located.

[0057] The electrical connection between the outer conductor 182 of the coaxial cable 18 and the intersection 3 is made, for example, by using a connecting wire 4 made of conductor, in the manner shown in Figure 4. At one end of the connecting wire 4, the outer conductor 182 and the connecting wire 4 are crimped together by a crimping component 4A. At the other end of the connecting wire 4, a fitting 4B is attached and fastened to the hole 3A of the intersection 3 with a fastening component 5 such as a bolt. This electrically connects the outer conductor 182 and the intersection 3 via the connecting wire 4. However, the electrical connection between the outer conductor 182 of the coaxial cable 18 and the intersection 3 is not limited to the method shown in Figure 4. For example, the other end of the connecting wire 4 may be formed in a film-like (planar) shape and placed at the intersection 3, thereby connecting the outer conductor 182 and the intersection 3 by capacitive coupling. Alternatively, the base 11 may have a metal fixing bracket and be directly fastened to the vehicle body 1.

[0058] <<Characteristics of the 20-inch dipole antenna>> Next, the characteristics of the dipole antenna 20 according to this embodiment will be explained using a comparison with a shark fin antenna.

[0059] Figure 5 shows an example of the frequency characteristics of the gain in the vertical polarization component of the dipole antenna 20. Figure 6 shows an example of the frequency characteristics of the gain in the horizontal polarization component of the dipole antenna 20.

[0060] In Figures 5 and 6, the horizontal axis represents frequency, and the vertical axis represents gain. Furthermore, in Figures 5 and 6, the results for the dipole antenna 20 of this embodiment described above are shown with a solid line, and the results for the comparative antenna (shark fin antenna) are shown with a dashed line. Here, the results are shown for the FM broadcast frequency band of 76MHz to 108MHz.

[0061] In both the case of the vertical polarization component shown in Figure 5 and the case of the horizontal polarization component shown in Figure 6, the dipole antenna 20 of this embodiment shows better gain results than the antenna of the comparative example. Furthermore, in the case of the comparative example antenna, in both the case of the vertical polarization component and the horizontal polarization component, the gain peaks around 85 MHz, and drops off below that point and to the wider frequency range. However, in the case of the dipole antenna 20 of this embodiment, in the case of the vertical polarization component shown in Figure 5, the gain fluctuations are small across the entire frequency band for FM broadcasting (76 MHz to 108 MHz). Also, in the case of the horizontal polarization component shown in Figure 6, the gain fluctuations relative to the peak are smaller compared to the comparative example.

[0062] From the above, these results show that the dipole antenna 20 of this embodiment can achieve higher gain and wider bandwidth compared to the shark fin antenna of the comparative example. Therefore, in this embodiment, not only is it possible to miniaturize the antenna device 10, but it is also possible to achieve higher gain and wider bandwidth.

[0063] <<Installation location of antenna device 10>> Figure 7 shows an example of the average gain of the antenna device 10 at different installation locations.

[0064] In Figure 7, in vehicle 1, position A is the rear roof 2F, position B is the center reinforcement 2E, position C is the side roof 2G, and position D is the B pillar 2B. As shown in Figure 7, it can be seen that the dipole antenna 20 can secure a stable gain regardless of the installation location.

[0065] <<Variation>> Figure 8 is an explanatory diagram of modified antenna devices 10A and dipole antenna 20A.

[0066] In the antenna device 10 of this embodiment described above, one element of the dipole antenna 20 was an element inside the antenna device 10 (a plate-shaped element 13 and a helical element 15), and the other element of the dipole antenna 20 was a conductor frame 2 of the vehicle 1.

[0067] As shown in Figure 8, in the conductor frame 2 of the vehicle 1, some conductor parts (in this case, for example, part of the center reinforcement 2E) may not be electrically connected to other conductor parts by being connected with resin members or the like. Hereinafter, the conductor parts of the conductor frame 2 that are not electrically connected to other conductor parts may be referred to as "floating conductor parts". In this case, this floating conductor part (part of the center reinforcement 2E) can be used as one element of the dipole antenna 20A, instead of an element inside the antenna device 10A. Alternatively, a conductor part that is electrically connected to other conductor parts and can be used as ground (in this case, the B pillar 2B and the side roof 2G) can be used as the other element of the dipole antenna 20A.

[0068] In other words, in this modified dipole antenna 20, both elements of the dipole antenna 20A use the conductor frame 2 of the vehicle 1, making it possible to further miniaturize the antenna device 10A.

[0069] ==Summary== According to this specification, antenna devices in the following embodiments are provided.

[0070] (Aspect 1) Embodiment 1 is an antenna device comprising a signal line side conductor, a ground side conductor, and an antenna element to which the signal line side conductor is electrically connected, wherein at least the antenna element and the conductor frame of a vehicle to which the ground side conductor is electrically connected form a dipole antenna.

[0071] According to the above-described embodiment, the degree of freedom in the layout of the antenna device in a vehicle can be improved.

[0072] (Aspect 2) In embodiment 2, the conductor frame has a first conductor portion having an angle with respect to the horizontal plane and a second conductor portion whose angle with respect to the horizontal plane is smaller than the angle of the first conductor portion with respect to the horizontal plane, and the ground-side conductor is electrically connected to at least one of the first end of the first conductor portion and the second end of the second conductor portion located on the side of the first end.

[0073] According to the above-described embodiment, a dipole antenna can be formed using at least one of the conductor portion extending vertically and the conductor portion extending horizontally in the grid structure formed on the conductor frame of the vehicle, and the gain can be further improved.

[0074] (Aspect 3) In embodiment 3, a first axis along the direction in which the first conductor portion extends and a second axis along the direction in which the second conductor portion extends intersect at a predetermined intersection, and the ground-side conductor is electrically connected to at least one of the first end and the second end on the side where the interior angle formed by the first axis and the second axis at the intersection is located.

[0075] According to the above-described embodiment, a dipole antenna can be formed using at least one of the conductor portion extending vertically and the conductor portion extending horizontally in the grid structure formed on the conductor frame of the vehicle, and the gain can be further improved.

[0076] (Aspect 4) In embodiment 4, the dipole antenna is an antenna for linear polarization.

[0077] According to the above-described embodiment, the gain can be improved in both the vertical and horizontal components of linear polarization.

[0078] According to this specification, dipole antennas in the following embodiments are provided.

[0079] (Aspect 5) Embodiment 5 is a dipole antenna comprising a signal line side antenna element to which a signal line side conductor is electrically connected, and a ground side antenna element which is at least a vehicle conductor frame to which a ground side conductor is electrically connected.

[0080] According to the above-described embodiment, the degree of freedom in the layout of the antenna device in a vehicle can be improved.

[0081] According to this specification, vehicles in the following embodiments are provided.

[0082] (Aspect 6) Embodiment 6 is a vehicle comprising a conductor frame and an antenna device, wherein the antenna device has a signal line side conductor, a ground side conductor, and an antenna element to which the signal line side conductor is electrically connected, and the antenna element and the conductor frame to which the ground side conductor is electrically connected form a dipole antenna.

[0083] According to the above-described embodiment, the degree of freedom in the layout of the antenna device in a vehicle can be improved.

[0084] The embodiments described above are provided to facilitate understanding of the present invention and are not intended to limit its interpretation. Furthermore, the present invention may be modified or improved without departing from its spirit, and it goes without saying that the present invention includes equivalents thereof. [Explanation of Symbols]

[0085] 1 vehicle, 2 conductor frames, 10 antenna devices, 20 dipole antennas 31 Signal line conductor, 32 Ground conductor

Claims

1. It comprises a signal line side conductor, a ground side conductor, and an antenna element to which the signal line side conductor is electrically connected, At a minimum, the antenna element and the vehicle's conductor frame to which the ground-side conductor is electrically connected form a dipole antenna. Antenna device.

2. The aforementioned conductor frame is A first conductor portion having an angle with respect to the horizontal plane, It has a second conductor portion whose angle with respect to the horizontal plane is smaller than the angle of the first conductor portion with respect to the horizontal plane, The ground-side conductor is electrically connected to at least one of the first end of the first conductor portion and the second end of the second conductor portion located on the side of the first end. The antenna device according to claim 1.

3. A first axis along the direction in which the first conductor portion extends and a second axis along the direction in which the second conductor portion extends intersect at a predetermined intersection, and on the side where the interior angle formed by the first axis and the second axis at the intersection is located, The ground-side conductor is electrically connected to at least one of the first end and the second end. The antenna device according to claim 2.

4. The aforementioned dipole antenna is an antenna for linear polarization. The antenna device according to claim 2 or 3.

5. The signal line side antenna element, to which the signal line side conductor is electrically connected, A conductor frame of a vehicle comprising a ground-side antenna element to which the ground-side conductor is electrically connected, Dipole antenna.

6. A vehicle comprising a conductor frame and an antenna device, The aforementioned antenna device is It comprises a signal line side conductor, a ground side conductor, and an antenna element to which the signal line side conductor is electrically connected. The antenna element and the conductor frame to which the ground conductor is electrically connected form a dipole antenna. vehicle.

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