JP6775373B2 - In-vehicle antenna device - Google Patents

Description

The present invention relates to an in-vehicle antenna device.

As an in-vehicle antenna device mounted on a vehicle, it is known to use a monopole antenna having a length of 1/4 of the wavelength of the received radio wave (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2013-232772

When the in-vehicle antenna device, which is a monopole antenna, is arranged inside the passenger compartment of the vehicle, the in-vehicle antenna device has openings such as windshield and rear glass in order to prevent radio waves from being blocked by the metal vehicle body. It is placed in the department. At this time, the in-vehicle antenna device needs to be arranged close to the vehicle body such as the A pillar and the roof head in order to secure the visibility of the occupants of the vehicle such as the driver. If the in-vehicle antenna device is arranged close to the vehicle body, the reception sensitivity may decrease. Further, in an in-vehicle antenna device, in a frequency band having a relatively long wavelength such as a VHF band, it is necessary to increase the antenna length according to the wavelength, but from the viewpoint of design or the like, the antenna length that can be arranged cannot be increased, and the in-vehicle antenna device cannot be installed. The reception sensitivity of the antenna device may be further reduced.

An object of the present invention is to solve such a problem, and to provide an in-vehicle antenna device capable of maintaining good reception sensitivity even when the antenna device is arranged close to the vehicle body.

In order to realize the above object, the in-vehicle antenna device according to the present invention has a loop antenna in which at least a part thereof is arranged in close proximity to a conductive first member which is a part of a vehicle body, and the loop antenna. The ground end is connected to one end of a conductive second member extending in a direction away from the first member, and the ground end of the loop antenna and one end of the first member are other conductive parts of the second member and the vehicle body. It is characterized by being electrically connected via a sex member.

Further, in the vehicle-mounted antenna device according to the present invention, the loop antenna and the first member are electromagnetically coupled or capacitively coupled, and the loop antenna, the first member, the second member and the conductive member are electromagnetically coupled or capacitively coupled. It is preferable to form a current loop.

Further, in the vehicle-mounted antenna device according to the present invention, the effective length of the current loop is preferably approximately 1/4 of the wavelength of the signal received by the loop antenna.

Further, in the vehicle-mounted antenna device according to the present invention, it is preferable that the first member is a pillar and the ground end of the loop antenna is arranged at a position separated by a predetermined distance in a direction perpendicular to the extending direction of the pillar.

Further, in the in-vehicle antenna device according to the present invention, the pillar is an A pillar, and the conductive member includes a reinforcement located in front of the passenger compartment of the vehicle and extending from one side surface of the vehicle to the other side surface. Is preferable.

Further, the in-vehicle antenna device according to the present invention further includes a signal amplifier that amplifies the signal received by the loop antenna, and the second member extends from the reinforcement toward the ground end of the loop antenna and supports the signal amplifier. It is preferable that the support member is a support member.

Further, the in-vehicle antenna device according to the present invention further includes a signal amplifier supported by an insulating support member extending from the reinforcement toward the ground end of the loop antenna and amplifying the signal received by the loop antenna. The two members are preferably conductors that connect the reinforcement and the ground end of the loop antenna.

Further, the in-vehicle antenna device according to the present invention further has a signal amplifier that amplifies the signal received by the loop antenna, the second member is connected to the vehicle body without passing through the reinforcement, and the signal amplifier is attached to the upper end. It is preferable to include a substantially L-shaped conductive bracket.

According to the present invention, the in-vehicle antenna device can maintain good reception sensitivity even when it is arranged close to the vehicle body.

It is a figure which shows the operating principle of the vehicle-mounted antenna device which concerns on embodiment. (A) is a diagram showing an in-vehicle antenna device according to a comparative example, (b) is a diagram showing an equivalent antenna of the in-vehicle antenna device shown in (a), and (c) is a diagram showing an equivalent antenna shown in (b). It is a figure which shows the simulation model, (d) is a figure which shows the equivalent antenna of the vehicle-mounted antenna device which concerns on embodiment, (e) is a figure which shows the simulation model of the equivalent antenna shown by (d). (A) is a diagram showing the result of simulation by the simulation model shown in FIG. 2 (c) and the result of simulation by the simulation model shown in FIG. 2 (e), and (b) is a diagram showing the horizontal axis of (a). It is a figure for doing. It is a figure which shows the vehicle-mounted antenna device which concerns on 1st Embodiment. It is a figure which shows the vehicle-mounted antenna device which concerns on 2nd Embodiment. (A) is a diagram showing the vehicle-mounted antenna device according to the third embodiment, and (b) is a partially exploded view of the vehicle-mounted antenna device shown in (a). It is a figure which shows the vehicle-mounted antenna device which concerns on 4th Embodiment.

The vehicle-mounted antenna device according to the present invention will be described with reference to the following drawings. However, it should be noted that the technical scope of the present invention is not limited to those embodiments, but extends to the equivalent of the invention described in the claims.

(Operating principle of the in-vehicle antenna device according to the embodiment)
Before explaining the configuration and function of the vehicle-mounted antenna device according to the embodiment, the operating principle of the vehicle-mounted antenna device according to the embodiment will be described.

The inventors of the present invention arrange a narrow loop antenna close to a conductive rod-shaped member such as an A pillar, and form a ground current loop having a length substantially equal to the effective length of the loop antenna. As a result, we have found an antenna device that can achieve both design and reception sensitivity.

FIG. 1 is a diagram showing an operating principle of the vehicle-mounted antenna device according to the embodiment.

The in-vehicle antenna device 1 has a narrow loop antenna 10. The length of the loop antenna 10 in the longitudinal direction is approximately 1/8 of the wavelength λ of the signal received by the loop antenna 10, and the effective length of the loop antenna 10 is approximately 1/4 of the wavelength λ of the signal received by the loop antenna 10. Is. One side of the long side of the loop antenna 10 is arranged close to the pillar 20 extending in the first direction. Since one side of the loop antenna 10 is arranged close to the pillar 20, one side of the loop antenna 10 and the pillar 20 are electromagnetically or capacitively coupled via electromagnetic coupling or capacitive coupling.

The pillar 20 is a rod-shaped member extending in the first direction, and functions as a window pillar of a vehicle. The pillar 20 is located in front of the passenger compartment of the vehicle, the A pillar, which is also called the front pillar or the front pillar upper, and the B pillar, which is located between the front seat and the rear seat of the vehicle and is also called the center pillar. And C-pillars located behind the rear seats of the vehicle. In one example, the pillar 20 is an A pillar.

The ground end 11 of the loop antenna 10 extends at a position separated from the pillar 20 by a predetermined distance in the second direction orthogonal to the first direction, in a direction separated from the pillar 20, specifically, in a direction opposite to the extending direction of the pillar 20. It is connected to one end of the conductive second member 21. The ground end 11 of the loop antenna 10 is arranged at a position separated from the pillar 20 by a predetermined distance. The length of the second member 21 is approximately 1/8 of the wavelength λ of the signal received by the loop antenna 10.

The second member 21 has one end connected to the other end of the second member 21 and extends in the second direction, and one end is connected to the other end of the third member 22 and extends in the first direction. It is electrically connected to the pillar 20 via the fourth member 23. The loop antenna 10, the pillar 20, the second member 21, the third member 22, and the fourth member 23 form a ground current loop through an electromagnetic coupling or a capacitive coupling between the loop antenna 10 and the pillar 20. The lengths of the second member 21 and the fourth member 23 are both approximately 1/8 of the wavelength λ of the signal received by the loop antenna 10. The length of the ground current loop formed by the loop antenna 10, the pillar 20, the second member 21, the third member 22, and the fourth member is approximately 1/4 of the wavelength λ of the signal received by the loop antenna 10.

The second member 21 is, for example, a conductive support member that supports a signal amplifier (not shown). Further, in another example, the second member 21 is a conductor having one end connected to the ground end 11 of the loop antenna 10 and the other end connected to the third member.

The third member 22 is, in one example, a reinforcement, and more specifically, a reinforcement, also called an instrument panel reinforcement, which is located in front of the passenger compartment of the vehicle and extends from one side of the vehicle to the other side. is there.

The fourth member 23 is, in one example, a member located below the glass of the side member of the vehicle and electrically connected to the pillar 20 and the third member 22, and in one example, in front of the passenger compartment of the vehicle. It is a front pier low located.

In the in-vehicle antenna device 1, the loop antenna 10 is narrow and has one long side close to the pillar 20, so that the loop antenna 10 can be accommodated inside a trim cover (not shown) and is visible to the occupants of the vehicle. There is no risk of it being done, and the design is guaranteed.

Further, in the in-vehicle antenna device 1, the ground current loop is formed by the loop antenna 10, the pillar 20, the second member 21, the third member 22, and the fourth member, so that the radiation resistance is increased and the loop antenna 10 receives. Performance is improved.

Further, in the vehicle-mounted antenna device 1, the loop antenna 10, the pillar 20, the second member 21, the third member 22, and the fourth member 23 are formed by electromagnetic coupling or capacitive coupling between the loop antenna 10 and the pillar 20. Since a current loop is formed, a strong induced current is generated in the loop antenna 10. In the in-vehicle antenna device 1, the antenna gain and reception performance of the loop antenna 10 are improved by generating a strong induced current in the loop antenna 10 by the current loop formed by the loop antenna 10 and the pillars 20 to the fourth member 23. be able to.

FIG. 2A is a diagram showing an in-vehicle antenna device according to a comparative example, FIG. 2B is a diagram showing an equivalent antenna of the in-vehicle antenna device shown in FIG. 2A, and FIG. 2C is a diagram showing an equivalent antenna. It is a figure which shows the simulation model of the equivalent antenna shown in FIG. 2 (b). FIG. 2D is a diagram showing an equivalent antenna of the vehicle-mounted antenna device 1, and FIG. 2E is a diagram showing a simulation model of the equivalent antenna shown in FIG. 2D. FIG. 3A is a diagram showing the result of simulation by the simulation model shown in FIG. 2C and FIG. 3B is a diagram showing the result of simulation by the simulation model shown in FIG. 2E, and FIG. 3B is FIG. 3A. It is a figure for demonstrating the horizontal axis of). In FIG. 3A, the horizontal axis represents the position of the loop antenna and the vertical axis represents the current value. More specifically, P1 shown on the horizontal axis of FIG. 3A corresponds to one short side near the feeding point of the loop antenna 10 shown in FIG. 3B, and P2 is the long side of the loop antenna 10. Corresponds to, and P3 corresponds to the other short side of the loop antenna 10. Further, in FIG. 3 (a), the curve 201 shows the result of the simulation by the simulation model shown in FIG. 2 (c), and the curve 202 shows the result of the simulation by the simulation model shown in FIG. 2 (e).

As shown in FIG. 2A, the vehicle-mounted antenna device 901 according to the comparative example has a narrow loop antenna 910, similarly to the vehicle-mounted antenna device 1. The longitudinal length of the loop antenna 910 is approximately 1/8 of the wavelength λ of the signal received by the loop antenna 910, and the effective length of the loop antenna 910 is approximately 1/4 of the wavelength λ of the signal received by the loop antenna 910. Is. The loop antenna 910 is grounded between the pillar 920 and the vehicle body.

As shown by the solid line in FIG. 2B, in the vehicle-mounted antenna device 901, only the loop antenna 910 operates.

On the other hand, as shown by the broken line in FIG. 2D, in the vehicle-mounted antenna device 1, the loop antenna 10 and the current loop formed by the pillars 20 to the fourth member 23 operate as a folded dipole. The current loop formed by the loop antenna 10 and the pillars 20 to the fourth member 23 operates as a folded dipole, so that the operation of the loop antenna 10 is duplicated in addition to the operation of the loop antenna 10 as a loop antenna. In the vehicle-mounted antenna device 1, the operation of the loop antenna 10 is duplicated, so that the high-frequency current is concentrated on the loop antenna 10.

As shown in FIG. 3A, in the vehicle-mounted antenna device 1, the high-frequency current can be concentrated on the loop antenna 10, so that the current flowing through the loop antenna 10 can be made larger than the current flowing through the loop antenna 910. it can.

Further, in the vehicle-mounted antenna device 1, the reception of the loop antenna 10 is performed by making the effective length of the ground current loop formed by the loop antenna 10 and the pillars 20 to the fourth member 23 substantially equal to the effective length of the loop antenna 10. Performance can be further improved. In the in-vehicle antenna device 1, the reception performance of the loop antenna 10 can be further improved by arranging the capacitive element and matching the impedance.

When the frequency of the signal received by the loop antenna 10 is in the VHF band and the pillar 20 is the A pillar, the length of the long side of the loop antenna 10 is the wavelength of the signal received by the loop antenna 10 from the viewpoint of versatility. It is preferably about 1/8 of λ. That is, from the viewpoint of versatility, the effective length of the loop antenna 10 is preferably approximately 1/4 of the wavelength λ of the signal received by the loop antenna 10.

Further, in the in-vehicle antenna device 1, since the ground current loop is formed by using the members forming the vehicle body such as the pillar 20, the third member 22, and the fourth member 23, an additional ground current loop is formed. The number of parts can be minimized and the manufacturing cost can be reduced.

Further, in the in-vehicle antenna device 1, the A pillar may be used as the pillar 20 and the instrument panel reinforcement may be used as the second member 21. By using the pillar as the pillar 20 and the instrument panel force as the third member 22, the distance between the loop antenna 10 and the in-vehicle device (not shown) mounted on the instrument panel can be shortened.

(Configuration and Function of In-Vehicle Antenna Device According to First Embodiment)
FIG. 4 is a diagram showing an in-vehicle antenna device according to the first embodiment.

The in-vehicle antenna device 2 includes a loop antenna 30, a signal amplifier 33, and an insulator 35. The loop antenna 30 is wound around a narrow rectangular parallelepiped insulator 35 to form a narrow rectangular loop shape. One end of the loop antenna 30 is connected to the feeding point 31 of the signal amplifier 33, and the other end of the loop antenna 30 is connected to the ground end 32 of the signal amplifier 33. The loop antenna 30 and the insulator 35 are housed inside a trim cover (not shown). The ground end 32 of the signal amplifier 33 is arranged at a position separated from the pillar 40 by a predetermined distance in a direction orthogonal to the extending direction of the pillar 40.

One long side of the loop antenna 30 is arranged close to the pillar 40. The length of the long side of the loop antenna 30 is approximately 1/8 of the wavelength λ of the signal received by the loop antenna 30, and the effective length of the loop antenna 30 is approximately 1/4 of the wavelength λ of the signal received by the loop antenna 30. Is. One side of the loop antenna 30 and the pillar 40 are electromagnetically or capacitively coupled.

The signal amplifier 33 is supported by a metal support member 41, amplifies a signal received via the loop antenna 10, and outputs the signal to an in-vehicle device (not shown). The signal amplifier 33 is grounded to the support member 41 at the amplifier grounding point 34. When the signal amplifier 33 is grounded to the support member 41, the loop antenna 30 is grounded to the support member 41 via the signal amplifier 33.

The pillar 40 is a rod-shaped conductive member, and is an A pillar that is located in front of the passenger compartment of the vehicle and functions as a window pillar of the vehicle.

The support member 41 is a metal member extending vertically from the reinforcement 42, and the length of the support member 41 is approximately 1/8 of the wavelength λ of the signal received by the loop antenna 30. The support member 41 is one of the members extending in the vertical direction from the reinforcement 42.

The reinforcement 42 is a metal member that extends in the horizontal direction to form a vehicle body. In one example, the reinforcement 42 is an instrument panel reinforcement that is located in front of the passenger compartment of the vehicle and extends from one side of the vehicle to the other side. One end of the reinforcement 42 is joined to the pillar row 43. The length of the reinforcement 42 between the connection point of the support member 41 and the connection point of the pillar row 43 is substantially equal to the length of the short side of the loop antenna 30, which is very short compared to the length of the support member 41.

The pillar row 43 is a metal member that extends in the vertical direction to form a vehicle body, and its upper end is connected to the pillar 40.

The loop antenna 30, the support member 41, the reinforcement 42, and the pillar row 43 form a ground current loop via electromagnetic coupling or capacitive coupling between the loop antenna 30 and the pillar 40. The effective length of the ground loop formed by the loop antenna 30, the support member 41, the reinforcement 42, and the pillar row 43 is substantially equal to the effective length of the loop antenna 30, and is approximately 1/4 of the wavelength λ of the signal received by the loop antenna 30. Is.

(Operational effect of the in-vehicle antenna device according to the first embodiment)
In the vehicle-mounted antenna device according to the first embodiment, since the loop antenna and the insulator are housed inside a trim cover (not shown), there is no possibility of being visually recognized by the occupants of the vehicle, and the design is ensured.

Further, in the in-vehicle antenna device according to the first embodiment, the ground current loop is formed by the loop antenna, the pillar, the support member, the reinforcement and the pillar row, so that the radiation resistance is increased and the reception performance of the loop antenna is improved. ..

Further, the vehicle-mounted antenna device according to the first embodiment generates a strong induced current in the loop antenna via a current loop formed by a loop antenna, pillars, support members, reinforcements, and pillar rows. The in-vehicle antenna device according to the first embodiment can improve the antenna gain and reception performance of the loop antenna by generating a strong induced current in the loop antenna by the loop antenna and the current loop formed by the pillar to the pillar row. it can.

Further, in the in-vehicle antenna device according to the first embodiment, the reception performance of the loop antenna is improved by making the effective length of the ground current loop formed by the loop antenna and the pillar to the pillar row substantially equal to the effective length of the loop antenna. It can be improved further. In the in-vehicle antenna device according to the first embodiment, the reception performance of the loop antenna can be further improved by arranging the capacitive element and matching the impedance.

When the frequency of the signal received by the loop antenna 30 is in the VHF band, the length of the long side of the loop antenna 10 is approximately 1/8 of the wavelength λ of the signal received by the loop antenna 30 from the viewpoint of versatility. Is preferable. That is, from the viewpoint of versatility, the effective length of the loop antenna 30 is preferably approximately 1/4 of the wavelength λ of the signal received by the loop antenna 30.

Further, in the vehicle-mounted antenna device according to the first embodiment, the ground current loop is formed by using the members forming the vehicle body such as the pillar, the support member, the reinforcement, and the pillar row, so that the ground current loop can be formed. Additional components are minimized. The vehicle-mounted antenna device according to the first embodiment can reduce the manufacturing cost by minimizing the additional members for forming the ground current loop.

Further, in the in-vehicle antenna device 1, the distance between the loop antenna 30 and the in-vehicle device (not shown) mounted on the instrument panel is obtained by using the instrument panel reinforcement as the pillar 40 which is the A pillar and the instrument panel reinforcement 42 as the reinforcement 42. Can be shortened.

(Configuration and Function of In-Vehicle Antenna Device According to Second Embodiment)
FIG. 5 is a diagram showing an in-vehicle antenna device according to the second embodiment.

In the vehicle-mounted antenna device 3, the signal amplifier 33 is supported by the support member 46 instead of the support member 41, and the conductor 47 that electrically connects the loop antenna 30 and the reinforcement 42 is arranged. It is different from the in-vehicle antenna device 2. Since the configurations and functions of the components of the vehicle-mounted antenna device 3 other than the support member 46 and the conductor 47 are the same as the components and functions of the vehicle-mounted antenna device 2 having the same reference numerals, detailed description thereof will be omitted here. ..

The support member 46 is an insulating member whose lower end is connected to the reinforcement 42 via a connecting member (not shown) such as a screw and which supports the signal amplifier 33 at the upper end.

The conductor 47 is, for example, a copper wire, one end of which is connected to the loop antenna 30 and the other end of which is connected to the reinforcement 42 to electrically connect the loop antenna 30 and the reinforcement 42. The length of the conductor 47 is approximately 1/8 of the wavelength λ of the signal received by the loop antenna 30.

The loop antenna 30, the conductor 47, the reinforcement 42, and the pillar row 43 form a ground current loop via an electromagnetic coupling or a capacitive coupling between the loop antenna 30 and the pillar 40. The effective length of the ground loop formed by the loop antenna 30, the conductor 47, the reinforcement 42, and the pillar row 43 is substantially equal to the effective length of the loop antenna 30, and is approximately 1/4 of the wavelength λ of the signal received by the loop antenna 30. is there.

(Operational effect of the in-vehicle antenna device according to the second embodiment)
In the vehicle-mounted antenna device according to the second embodiment, since the signal amplifier 33 is supported by the support member connected to the reinforcement, the desired reception is performed even when the member suitable for supporting the signal amplifier 33 does not extend from the reinforcement. An in-vehicle antenna device having performance can be realized. Further, since an insulating material such as resin can be used for the support member, the weight can be reduced as compared with the case where a conductive member such as metal is used.

(Configuration and Function of In-Vehicle Antenna Device According to Third Embodiment)
FIG. 6A is a diagram showing the vehicle-mounted antenna device according to the third embodiment, and FIG. 6B is a partially exploded view of the vehicle-mounted antenna device shown in FIG. 6A.

The vehicle-mounted antenna device 4 differs from the vehicle-mounted antenna device 2 in that the bracket 51 is arranged in place of the support member 41 and the reinforcement 42. Since the configurations and functions of the components of the vehicle-mounted antenna device 4 other than the bracket 51 are the same as the configurations and functions of the components of the vehicle-mounted antenna device 2 having the same reference numerals, detailed description thereof will be omitted here.

The bracket 51 is a member having a substantially L-shaped cross-sectional shape having a conductivity in which the lower end is connected to the pillar row 43 by a pair of screws 52 and 53 and the signal amplifier 33 is attached to the upper end without a reinforcement. When the frequency of the signal received by the loop antenna 30 is in the VHF band, the length in the longitudinal direction of the flat plate portion extending in parallel with the pillar row 43 of the bracket 51 is the signal received by the loop antenna 30 from the viewpoint of versatility. It is preferable that the wavelength λ of the above is approximately 1/8. The length of the flat plate portion extending orthogonally to the pillar row 43 of the bracket 51 is substantially the same as the length of the loop antenna 30 in the lateral direction.

The loop antenna 30, the bracket 51, and the pillar row 43 form a ground current loop via electromagnetic coupling or capacitive coupling between the loop antenna 30 and the pillar 40. The effective length of the ground loop formed by the loop antenna 30, the bracket 51, and the pillar row 43 is substantially equal to the effective length of the loop antenna 30, and is approximately 1/4 of the wavelength λ of the signal received by the loop antenna 30.

(Operational effect of the in-vehicle antenna device according to the third embodiment)
In the vehicle-mounted antenna device according to the third embodiment, since the ground current loop is formed by the substantially L-shaped bracket connected to the vehicle body, when the reinforcement suitable for forming the ground current loop does not extend from the vehicle body. However, it is possible to realize an in-vehicle antenna device having a desired reception performance.

(Configuration and Function of In-Vehicle Antenna Device According to Fourth Embodiment)
FIG. 7 is a diagram showing an in-vehicle antenna device according to the fourth embodiment.

The vehicle-mounted antenna device 5 is different from the vehicle-mounted antenna device 4 in that the bracket 61 is arranged instead of the bracket 51 and the conductor 62 that electrically connects the loop antenna 30 and the pillar row 43 is arranged. Since the configurations and functions of the components of the vehicle-mounted antenna device 5 other than the bracket 61 and the conductor 62 are the same as the components and functions of the vehicle-mounted antenna device 4 having the same reference numerals, detailed description thereof will be omitted here.

The bracket 61 is a member having an insulating substantially L-shaped cross-sectional shape in which the lower end is connected to the pillar row 43 by a pair of screws 63 and 64 without the intervention of reinforcement and the signal amplifier 33 is attached to the upper end. The bracket 61 has a substantially L-shaped cross-sectional shape, but the cross-sectional shape is not substantially L-shaped as long as the lower end is connected to the pillar row 43 and the upper end can support the signal amplifier 33. May be good.

The conductor 62 is, for example, a copper wire, one end of which is connected to the loop antenna 30 and the other end of which is connected to the pillar row 43 to electrically connect the loop antenna 30 and the pillar row 43. The length of the conductor 62 is approximately 1/8 of the wavelength λ of the signal received by the loop antenna 30.

The loop antenna 30, the conductor 62, and the pillar row 43 form a ground current loop via an electromagnetic coupling or a capacitive coupling between the loop antenna 30 and the pillar 40. The effective length of the ground loop formed by the loop antenna 30, the conductor 62, and the pillar row 43 is substantially equal to the effective length of the loop antenna 30, and is approximately 1/4 of the wavelength λ of the signal received by the loop antenna 30.

(Operational effect of the in-vehicle antenna device according to the fifth embodiment)
In the vehicle-mounted antenna device according to the fourth embodiment, since the signal amplifier is supported by the bracket and the ground current loop is formed by the conductor connected to the vehicle body, the reinforcement suitable for forming the ground current loop extends from the vehicle body. Even if this is not the case, an in-vehicle antenna device having desired reception performance can be realized. Further, since an insulating material such as resin can be used for the bracket, the weight can be reduced as compared with the case where a conductive member such as metal is used.

(Modification example of the in-vehicle antenna device according to the embodiment)
In the vehicle-mounted antenna devices 1 to 3, the effective length of the ground current loop is substantially equal to the effective length of the loop antenna, but in the vehicle-mounted antenna device according to the embodiment, the effective length of the ground current loop is different from the effective length of the loop antenna. You may.

In the vehicle-mounted antenna devices 1 to 3, the loop antenna is arranged close to the pillar, but in the vehicle-mounted antenna device according to the embodiment, the loop antenna is close to the conductive member other than the pillar forming the vehicle body. It may be arranged.

1-3 In-vehicle antenna device 10, 30 Loop antenna 11 Ground end 20, 40 pillar (first member)
21 2nd member 22 3rd member 23 4th member 31 Feeding point 32 Ground end 33 Signal amplifier 34 Amplifier grounding point 41 Support member (2nd member)
42 Reinforce 43 Pillar row 46 Support member 47 Conductor (second member)
51 Bracket (second member)
61 Bracket 62 Conductor (second member)

Claims (8)

It has a loop antenna that is at least partly arranged in close proximity to a substantially rod-shaped conductive first member that is a part of the vehicle body.
The ground end of the loop antenna is connected to one end of a conductive second member that is vertically separated from the extending direction of the first member.
An in-vehicle antenna device, wherein the ground end of the loop antenna and one end of the first member are electrically connected via at least the second member. The loop antenna and the first member are electrically coupled to each other.
The vehicle-mounted antenna device according to claim 1, wherein the loop antenna, the first member, and the second member form a current loop through the coupling. The vehicle-mounted antenna device according to claim 2, wherein the effective length of the current loop is approximately 1/4 of the wavelength of the signal received by the loop antenna. The first member is a pillar, and the ground end of the loop antenna is arranged at a position separated by a predetermined distance in a direction perpendicular to the extending direction of the pillar, according to any one of claims 1 to 3. In-vehicle antenna device. The vehicle-mounted antenna device according to claim 4, wherein the second member includes a reinforcement extending from one side surface of the vehicle to the other side surface. It further has a signal amplifier that amplifies the signal received by the loop antenna.
The vehicle-mounted antenna device according to claim 5, wherein the second member further includes a support member extending from the reinforcement toward the ground end of the loop antenna and supporting the signal amplifier. The ground end of the loop antenna is supported by an insulating support member that is vertically separated from the extending direction of the first member.
The vehicle-mounted antenna device according to claim 1, wherein the second member is a conductor that connects the conductive portion of the vehicle body and the ground end of the loop antenna. It further has a signal amplifier that amplifies the signal received by the loop antenna.
The vehicle-mounted antenna device according to claim 1, wherein the second member includes a substantially L-shaped conductive bracket connected to the vehicle body without a reinforcement and to which the signal amplifier is attached at an upper end.

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