JP2011097350A - Antenna device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antenna device for vehicle that increases a gain of an antenna when UHF radio wave is emitted. <P>SOLUTION: The antenna device for vehicle includes a dipole antenna 50 provided inside a door handle of the vehicle, and radiates the UHF radio wave toward a communication area set around a vehicle door through the antenna 50. A gap is formed between an outer panel 40 of the vehicle door and the dipole antenna 50, and then an inner wall surface of the outer panel 40 to be arranged opposite to the dipole antenna 50 with a gap is used as a reflecting surface. The radio wave to be radiated from the dipole antenna 50 toward the outer panel 40 so as to increase the intensity of the radio wave to be radiated to the communication area, is reflected toward the communication area. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a vehicular antenna device for radiating radio waves to a communication area set around a vehicle body, for example.

  2. Description of the Related Art In recent years, for example, a so-called electronic key system is known that automatically executes unlocking of a vehicle door or the like when a user who has a portable device (electronic key) approaches the vehicle door. Conventionally, as such an electronic key system, for example, a system described in Patent Document 1 is known. FIG. 10 shows an outline of an electronic key system that is generally employed in the past, including the system described in Patent Document 1.

  As shown in FIG. 10, in this electronic key system, for example, a request signal is radiated from a transmission device 81 provided on a door of a vehicle 80 to a semicircular communication area S set around the vehicle door. In this electronic key system, a user receives a request signal emitted from the transmission device 81 and a portable device 90 that transmits a response signal including an identification code (ID code) to the received request signal. Possess. That is, when the user who has the portable device 90 enters the communication area S, a response signal is transmitted from the portable device 90. In this system, the response signal transmitted from the portable device 90 is received by the receiving device 82 provided in the vehicle interior, and is transmitted to the vehicle control device 83 that executes various controls for the vehicle 80 in an integrated manner. . In the control device 83, the ID code included in the transmitted response signal is collated with the ID code stored in the memory in the control device 83 in advance, and the ID codes match each other through this collation. When it is determined, the vehicle door is unlocked through a door lock device 84 provided on the vehicle door, for example. According to such an electronic key system, various operations of the vehicle 80 are automatically performed without direct manual operation by the user, so that the convenience of operation of the vehicle 80 is greatly improved. Become.

JP 2001-31333 A

  By the way, since the portable device 90 used for such an electronic key system generally uses a built-in battery as a power source, if the battery runs out, wireless communication with the vehicle 80 cannot be performed. For this reason, the user needs to replace the battery of the portable device 90 every time the battery runs out, and there is a possibility that the user may feel troublesome.

  Therefore, the inventors have proposed a method of eliminating the battery built in the portable device 90 by using the wireless power transmission technology. Specifically, a UHF band radio wave serving as a power supply voltage of the portable device 90 is radiated from the vehicle 80 to the portable device 90. When the portable device 90 receives the radio wave radiated from the vehicle 80, the portable radio device 90 rectifies the radio wave to obtain a power supply voltage. By adopting such a method, it is not necessary for the user to replace the battery of the portable device 90, so that the user's troublesomeness described above can be preferably eliminated.

  However, in the above-described electronic key system, when the portable device 90 enters the communication area S, it is necessary for the portable device 90 to be able to perform wireless communication. It is necessary to radiate radio waves to the entire communication area S. For this reason, there is a situation that a high gain antenna device that can radiate UHF band radio waves to the entire communication area S is desired.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a vehicle antenna device that can increase the gain of an antenna when radiating a radio wave in the UHF band.

  In order to solve the above-mentioned problems, an invention according to claim 1 includes an antenna provided in a vehicle body, and transmits UHF band radio waves toward a communication area set around the vehicle body through the antenna. A vehicle antenna device for radiating, wherein a gap is formed between an outer peripheral surface of the vehicle body and the antenna, and an outer peripheral surface of the vehicle body disposed opposite to the antenna with the gap is reflected. A radio wave reflecting structure that reflects radio waves radiated from the antenna toward the outer peripheral surface of the vehicle body toward the communication area in a manner that increases the intensity of radio waves radiated to the communication area. The gist is to have.

  According to this configuration, when radio waves are radiated from the antenna toward the communication area, the radio waves radiated from the antenna toward the outer peripheral surface of the vehicle body can be reflected to the communication area by the radio wave reflection structure. Therefore, the intensity of the radio wave radiated toward the communication area using the reflected radio wave can be increased. For this reason, the antenna gain can be increased when radiating radio waves in the UHF band.

  In this case, specifically, according to the invention described in claim 2, the antenna is disposed along the outer peripheral surface of the vehicle body, and the antenna of the vehicle body is opposed to the portion facing the antenna body. Is formed between the outer peripheral surface of the vehicle body and the antenna by adopting a configuration in which the concave portion is formed in the form of forming the gap, and the reflecting surface is composed of the inner wall surface of the concave portion facing the antenna. A structure in which a gap is formed can be easily realized.

  According to a third aspect of the present invention, in the vehicle antenna device according to the second aspect, the communication area set around the vehicle body is a semicircular communication area set around the vehicle door. The antenna is disposed inside a door handle provided in the vehicle door, and the concave portion is an outer peripheral surface of the vehicle door as a portion into which a user inserts a hand when holding the door handle. The gist of the present invention is that it is formed of a groove portion recessed in the wall.

  According to this configuration, since the groove portion recessed in the outer peripheral surface of the vehicle door can be used as the concave portion as a portion into which the user inserts his / her finger when gripping the door handle, the outer peripheral surface of the vehicle body A structure in which a gap is formed between the antenna and the antenna can be realized more easily.

  In this case, specifically, according to the invention described in claim 4, if a dipole antenna, for example, is used as an antenna for radiating UHF radio waves, the antenna can be easily arranged inside the door handle. Can be set up.

  According to a fifth aspect of the present invention, in the vehicle antenna device according to the fourth aspect, when the wavelength of the radio wave is “λ”, the length of the two elements is “λ / 4”. In addition, the gist is to satisfy the relationship of “5 mm ≦ L ≦ λ / 4” where L is the distance from the dipole antenna to the reflecting surface.

  When a dipole antenna is used as an antenna that emits radio waves in the UHF band, the distance L from the antenna to the reflecting surface is set to a length in the range of “5 mm” to “λ / 4 (> 5 mm)”. When set, the inventors have confirmed that the gain of the dipole antenna is larger than the absolute gain while forming a semicircular communication area around the vehicle door. Therefore, as described above, satisfying the relationship of “5 mm ≦ L ≦ λ / 4” is necessary for forming a semicircular communication area around the vehicle door and increasing the antenna gain. It is valid.

  The invention according to claim 6 is the vehicle antenna device according to claim 5, wherein the distance L from the dipole antenna to the reflecting surface is set to a length of “λ / 4”. It is said.

  When a dipole antenna is used as an antenna that radiates radio waves in the UHF band, if the distance from the antenna to the reflecting surface is set to a length of “λ / 4”, the distance between the dipole antenna and its feed line It has been confirmed by the inventors that it is easy to achieve impedance matching. Therefore, as described above, when the distance from the antenna to the reflecting surface is set to a length of “λ / 4”, a semicircular communication area is formed around the vehicle door, and the antenna gain is increased. In addition, the impedance matching between the dipole antenna and its feed line can be easily achieved.

  According to the vehicle antenna device of the present invention, the gain of the antenna can be increased when radiating a radio wave in the UHF band.

The block diagram which shows the system configuration | structure of the electronic key system of the vehicle using the apparatus about one Embodiment of the antenna apparatus for vehicles concerning this invention. Sectional drawing which shows the fracture | rupture sectional structure of the door handle apparatus of the vehicle in which the antenna apparatus for vehicles of the embodiment is provided. The top view which shows typically the structure of the vehicle antenna apparatus of the embodiment. (A)-(d) is a directivity figure which shows the directivity characteristic of a dipole antenna when the distance from a dipole antenna to an outer panel is set to "1mm", "5mm", "10mm", and "20mm", respectively. (A)-(d) is a directivity figure which shows the directivity characteristic of a dipole antenna when the distance from a dipole antenna to an outer panel is set to "40 mm", "80 mm", "160 mm", and "320 mm", respectively. The graph which shows the relationship between the distance from a dipole antenna to an outer panel, and the reflection coefficient in the feeding point of the dipole antenna. The top view which shows typically the structure about the modification of the antenna apparatus for vehicles of the embodiment. (A), (b) is a directivity figure which shows each directional characteristic of a dipole antenna and a V-type dipole antenna. The top view which shows typically the structure about the other modification of the vehicle antenna apparatus of the embodiment. The top view which shows typically the outline | summary of the electronic key system of the conventional vehicle.

  Hereinafter, an embodiment in which a vehicle antenna device according to the present invention is applied to a vehicle antenna device of an electronic key system will be described with reference to FIGS. The basic configuration of this electronic key system is the same as that of the electronic key system illustrated in FIG. FIG. 1 is a block diagram showing the system configuration of such an electronic key system. First, the configuration and operation of this electronic key system will be described more specifically with reference to FIG.

  As shown in FIG. 1, also in this electronic key system, various communication controls by wireless communication are executed between the in-vehicle device 10 mounted on the vehicle side and the portable device 20 carried by the user.

  Here, the in-vehicle device 10 is provided with a receiving device 12 that receives a UHF band response signal transmitted from the portable device 20 together with a transmitting device 11 that radiates a UHF band request signal to the communication area S. . The in-vehicle device 10 is also provided with a wireless power transmission device 13 that radiates a power radio wave that is a radio wave in the UHF band that is a power supply voltage of the portable device 20 to the communication area S. The in-vehicle device 10 is also provided with radiation control of the request signal by the transmission device 11, processing of the response signal received through the reception device 12, and radiation control of the power radio wave by the wireless power transmission device 13. It is executed in an integrated manner through the vehicle control device 14. Incidentally, the vehicle control device 14 is also a part that controls the control object 15 such as the door lock device described above.

  On the other hand, the portable device 20 is provided with a receiving device 21 that receives the request signal radiated from the in-vehicle device 10 and a transmitting device 22 that transmits the response signal to the in-vehicle device 10 in response to the received request signal. Yes. Then, the generation of the response signal based on the request signal received through the receiving device 21 and the transmission control of the generated response signal through the transmitting device 22 are also provided in the portable device 20. It is performed through the whole. Further, the portable device 20 stores the electric energy rectified by the rectifier 24 together with the rectifier 24 that receives and rectifies the power radio wave radiated from the in-vehicle device 10, and stores the electric energy rectified by the rectifier 24. There is also provided a power supply device 25 that generates a power supply voltage for operating 23 and the like.

  In the electronic key system configured as described above, when power radio waves are radiated from the wireless power transmission device 13 to the communication area S via the antenna device A1, the portable device 20 possessed by the user. Suppose that the vehicle enters the communication area S, a signal is exchanged between the in-vehicle device 10 and the portable device 20 in the following manner. That is, in this system, the electric power radio wave radiated from the wireless power transmission device 13 is received by the rectifying device 24 via the antenna device A3, and the rectifying device 24 rectifies the electric power radio wave and supplies the electric energy. Is transmitted to the power supply device 25. When the electric energy is thus transmitted, the power supply device 25 accumulates the electric energy to generate a power supply voltage, and the generated power supply voltage is mounted on the portable device 20 such as the receiving device 21 or the portable device control device 23. These are applied to various electronic components to drive them. Subsequently, when a request signal is radiated from the transmitting device 11 to the communication area S via the antenna device A4, the radiated request signal is received by the receiving device 21 via the antenna device A2. The received request signal is transmitted to the portable device control device 23. When the request signal is transmitted in this way, the portable device control device 23 generates a response signal including an identification code (ID code) stored in the built-in memory and transmits it to the transmission device 22. The signal is transmitted to the in-vehicle device 10 via the antenna device A2. By transmitting the response signal in this way, the receiving device 12 receives the response signal via the antenna device A4 and transmits the received response signal to the vehicle control device 14. As a result, the vehicle control device 14 collates the ID code included in the transmitted response signal with the ID code stored in the memory built in the control device 14 as described above. Based on the determination that the ID codes match, the vehicle door is unlocked through the door lock mechanism that is the control target.

  By the way, in such an electronic key system, as described above, it is necessary to radiate a UHF band request signal and power radio waves to the communication area S, that is, a semicircular area set around the vehicle door. Therefore, in the present embodiment, the antenna devices A1 and A4 are provided on the door handle provided on the vehicle door in order to easily radiate the request signal and the electric power radio wave to the communication area S.

Next, the structure of the door handle device provided on the vehicle door will be described in detail with reference to FIG. FIG. 2 shows a partial sectional structure of the door handle device.
As shown in FIG. 2, a groove 41 serving as a portion into which a user's hand is inserted is recessed in the outer peripheral surface of the outer panel 40 of the vehicle door. In the door handle device 30, the groove 41 A door handle 31 is disposed along the outer panel 40 with a gap GP between the inner wall surface and the inner wall surface. Incidentally, the door handle 31 is formed of a highly rigid resin material, and the outer panel 40 is formed of a metal material such as high-tensile steel. A grip portion 31 a serving as a portion to be gripped by the user is formed at a portion of the door handle 31 that faces the groove portion 41. Further, at one end portion of the door handle 31, a rotating portion 33 that penetrates the outer panel 40 and is rotatably supported by a support member 42 provided therein is led out. Further, an operating portion 32 for operating a lever (not shown) of a door opening / closing mechanism that penetrates the outer panel 40 and is provided therein is led out to the other end portion of the door handle 31. That is, in this door handle device 30, if the user inserts a hand into the gap GP and grips the grip portion 31a and then pulls the door handle 31 in the direction indicated by the arrow a in the figure, the support member 42 The door handle 31 rotates in the direction in which the operation unit 32 is pulled out with the rotation axis as a rotation axis. At this time, if the vehicle door is not in the locked state, the lever is operated by the operation unit 32 to open the vehicle door.

  On the other hand, the transmitter 11, the receiver 12, the wireless power transmitter 13 (not shown), and the like are provided inside the outer panel 40, and the antenna connected to the transmitter 11 and the like via the feeder 11 a. Devices A1 and A4 are provided inside the door handle 31. In the drawing, the illustration of the antenna device A4 is omitted for convenience. For example, if the transmission device 11 or the wireless power transmission device 13 supplies power to the antenna devices A1 and A4 via the power supply line 11a, a request signal or the like is transmitted from the antenna devices A1 and A4 to the communication area S. Electric power radio waves will be emitted.

  Thus, in this embodiment, by arranging the antenna device A1 inside the door handle 31, between the outer peripheral surface of the outer panel 40 and the antenna device A1, in other words, the outer peripheral surface of the vehicle body and the antenna device. A gap GP is formed with A1. Incidentally, if the antenna device A1 is disposed inside the door handle 31 as described above, a gap can be easily formed between the antenna device A1 and the outer peripheral surface of the vehicle body using the groove 41. become.

Next, the structure of the antenna device A1 according to the present embodiment will be described in detail with reference to FIG. FIG. 3 schematically shows the structure of the antenna device A1.
As shown in FIG. 3, the antenna device A1 is basically constituted by a dipole antenna 50, and is substantially parallel to the inner wall surface of the groove 41, in other words, substantially the same as the outer panel 40. There are two elements 51 and 52 arranged in parallel, and a power feeding point 53 that is connected to the power feeding line 11a and feeds power to the elements 51 and 52. Incidentally, in this dipole antenna 50, when the wavelength of the radio wave in the UHF band is “λ”, the length of each element 51, 52 is “λ / 4”, that is, the total length of the antenna is “ This is a so-called half-wave dipole antenna set to a length of λ / 2 ”.

  By the way, in the electronic key system described above, since it is necessary to radiate UHF band radio waves such as the request signal and power radio wave to the entire communication area S, it is desired that the gain of the antenna device A1 is high.

  Therefore, in the present embodiment, the inner wall surface of the outer panel 40 disposed to face the dipole antenna 50 with the gap GP is used as a reflecting surface, more specifically, the inner wall surface of the groove 41 is used as a reflecting surface. The radio wave radiated toward is reflected toward the communication area S. The antenna gain is increased by increasing the strength of the radio wave radiated to the communication area S using the radio wave (reflected wave) reflected through the radio wave reflection structure. Specifically, in the antenna device A1 having the above-described configuration, the distance L from the dipole antenna 50 to the outer panel 40 is set to a length in the range of “5 mm” to “λ / 4 (> 5 mm)”. This is effective in forming the communication area S and increasing the gain of the dipole antenna 50. In particular, setting the distance L from the dipole antenna 50 to the outer panel 40 to a length of “λ / 4” is very effective in achieving impedance matching between the feed line 11 a and the dipole antenna 50. This has been confirmed by the inventors' simulation.

4 to 6 are graphs showing simulation results by the inventors. Next, the contents confirmed by the inventors will be described in detail with reference to FIGS.
First, the relationship between the distance L from the dipole antenna 50 to the outer panel 40 and the gain of the dipole antenna 50 will be described with reference to FIGS. 4 and 5. 4 (a) to 4 (d) and FIGS. 5 (a) to 5 (d), the same distance L is “1 mm”, “5 mm”, “10 mm”, “20 mm”, “40 mm”, “80 mm (≈ 6 is a graph showing the directivity characteristics of the dipole antenna 50 when set to “λ / 4)”, “160 mm”, and “360 mm”, respectively. In these drawings, as shown in FIG. 3, the feeding point 53 is the origin, the direction in which the two elements 51 and 52 extend is the x axis, and the axis orthogonal to the x axis is the y axis. , The clockwise angle θ (unit: “°”) around the feeding point 53 from the x-axis is the circumferential axis, and the radio wave intensity (unit: [dBi]) is the radial direction. Stay on the axis. Further, the upward direction in the figure is taken as the direction of the outside of the vehicle door, and the downward direction in the figure is the direction on the outer panel 40 side. Further, here, it is assumed that the outer panel 40 is an infinite iron plate.

  As shown in FIGS. 4A to 4D and FIGS. 5A and 5B, the distance L from the dipole antenna 50 to the outer panel 40 is a length in the range of “1 mm” to “80 mm”. When set to, radio waves are radiated so as to spread in a substantially semicircular shape around the dipole antenna 50 and outside the vehicle door. On the other hand, as shown in FIGS. 5C and 5D, when the same distance L is set to “160 mm” or “360 mm”, a heart shape is formed outside the vehicle door with the dipole antenna 50 as the center. Alternatively, radio waves are emitted so as to spread in a deformed heart shape. Therefore, in order to radiate radio waves to the semicircular communication area S set around the vehicle door, it is desirable to set the distance L to a length in the range of “1 mm” to “80 mm”.

  Next, the antenna gain when the distance L is set to a length in the range of “1 mm” to “80 mm” will be verified. First, as shown in FIG. 4A, when the distance L is set to a length of “1 mm”, the gain of the dipole antenna 50 is “−3.62 [dBi]”. Is smaller than the absolute gain (2.15 [dBi]). On the other hand, as shown in FIGS. 4B to 4D and FIGS. 5A and 5B, when the distance L is set to a length of “5 mm” to “80 mm”, a dipole is used. The gain of the antenna 50 can be made larger than its absolute gain, and the intensity of the wireless radio wave radiated to the communication area S can be increased.

  As described above, when the distance from the dipole antenna 50 to the outer panel 40 is L, the relationship “5 mm ≦ L ≦ 80 mm (≈λ / 4)” is satisfied. This is effective in forming a communication area and increasing the gain of the antenna.

  Next, a relationship between the distance L from the dipole antenna 50 to the outer panel 40 and the impedance matching relationship between the feed line 11a and the dipole antenna 50 will be described with reference to FIG. FIG. 6 is a graph showing the relationship between the distance L on the horizontal axis and the reflection coefficient at the feeding point 53 on the vertical axis.

  As shown in FIG. 6, the reflection coefficient of the dipole antenna 50 tends to increase as the distance L decreases, and particularly increases rapidly when the distance L is shorter than “40 mm”. That is, in the range where the distance L is shorter than “40 mm”, it is difficult to feed power from the feed line 11 a to the dipole antenna 50, and impedance matching between the feed line 11 a and the dipole antenna 50 is taken. Is difficult to understand. It has been confirmed by the inventors that this is because the impedance of the dipole antenna 50 becomes smaller as the distance L becomes shorter, that is, the closer the dipole antenna 50 and the outer panel 40 are. Therefore, according to this graph, it can be understood that impedance matching between the feeder 11a and the dipole antenna 50 can be easily achieved by setting the distance L to be longer than “80 mm”.

  Therefore, in the vehicle antenna device of the present embodiment, the distance L is set to “80 mm”, that is, “λ / 4” based on the simulation results illustrated in FIGS. 4 to 6. I have to. According to such a configuration, as is clear from the simulation results, a semicircular communication area can be formed around the vehicle door, and the gain of the antenna can be increased. Impedance matching with the antenna 50 is facilitated.

As described above, according to the vehicle antenna device according to the present embodiment, the following effects can be obtained.
(1) After the dipole antenna 50 is disposed inside the door handle 31, the distance L from the dipole antenna 50 to the outer panel 40, that is, the distance from the dipole antenna 50 to the vehicle body is a length of “λ / 4”. Was set to. As a result, a semicircular communication area can be formed around the vehicle door, the antenna gain can be increased, and impedance matching between the feeder 11a and the dipole antenna 50 can be easily performed. .

  (2) After the dipole antenna 50 is disposed inside the door handle 31, a groove 41 that is recessed in the outer peripheral surface of the outer panel 40 is used as a portion for inserting a hand when the user grips the door handle 31. Thus, a gap is formed between the dipole antenna 50 and the outer peripheral surface of the outer panel 40. Thereby, a configuration in which a gap is formed between the dipole antenna 50 and the outer peripheral surface of the outer panel 40 can be easily realized.

In addition, the said embodiment can also be implemented with the following forms which changed this suitably.
In the above embodiment, the distance L from the dipole antenna 50 to the outer panel 40 is set to a length of “λ / 4”, but the relationship “5 mm ≦ L <80 mm (≈λ / 4)” is satisfied. The distance L may be set as described above. Even such a configuration is effective in forming the semicircular communication area S around the vehicle door and increasing the gain of the antenna.

  In the above embodiment, the dipole antenna 50 is used as an antenna for transmitting a radio wave in the UHF band. Instead, for example, as shown in FIG. A so-called V-shaped dipole antenna 60 that is bent in a V shape on the body side may be used. FIGS. 8A and 8B are graphs showing the directivity characteristics of the dipole antenna 50 and the V-type dipole antenna 60 obtained through simulations by the inventors as diagrams corresponding to FIGS. 4 and 5 described above. It is. Here, for convenience, it is assumed that the outer panel 40 is a “500 mm” square plate. Further, the same plate material is disposed so that the center thereof is located on the y-axis, and the distance between the dipole antenna 50 and the plate material and the distance between the V-type dipole antenna 60 and the plate material are set to “15 mm”, respectively. . Furthermore, as shown in FIG. 7, the case where the bending angle of the V-type dipole antenna 60 is φ and the angle φ is set to “160 °” is illustrated. 8A and 8B, in the dipole antenna 50, the radio field intensity on the x-axis is “−9.9 [dBi]”, but in the V-type dipole antenna 60, the x-axis The upper radio wave intensity is “−6.6 [dBi]”. That is, as compared with the dipole antenna 50, the V-type dipole antenna 60 can enhance the antenna directivity in the x-axis direction, that is, in the direction along the vehicle body. For this reason, since the said communication area S can be expanded in the direction along the vehicle body, the null point on the communication area S can be improved.

  In place of the dipole antenna 50, a folded dipole antenna 70 having a structure in which the tip ends of two elements 71 and 72 are connected by an element 73 as shown in FIG. 9 may be used. As described above, the inventors have confirmed that as the distance from the dipole antenna 50 to the outer panel 40 becomes shorter, the impedance of the dipole antenna 50 becomes smaller and it becomes difficult to achieve impedance matching between the feeder and the antenna. . Therefore, if the folded dipole antenna 70 having a higher impedance than the dipole antenna is used, the impedance between the feed line and the antenna can be reduced even when the distance from the antenna to the outer panel is shorter than, for example, “λ / 4”. It becomes easy to take alignment.

  In the above embodiment, a dipole antenna is used as an antenna that emits radio waves in the UHF band. However, in accordance with the shape of the door handle of various vehicles, for example, a linear antenna such as a monopole antenna or an inverted F A plate antenna such as an antenna or an inverted L antenna may be used.

In the above embodiment and its modifications, the antenna is provided inside the door handle 31 in order to provide a gap between the antenna such as the dipole antenna 50 and the vehicle body. Instead of this, for example, the antenna is housed in an appropriate resin case or the like, and the resin case is fixedly disposed along the outer peripheral surface of the vehicle body, and an appropriate recess is formed in the portion of the vehicle body facing the antenna. By forming, a gap may be provided between the antenna and the vehicle body. By adopting such a configuration, for example, it is possible to mount the vehicle antenna device according to the present embodiment on a vehicle in which it is difficult to provide an antenna inside the door handle. In short, a gap is formed between the outer peripheral surface of the vehicle body and the antenna, and the outer peripheral surface of the vehicle body is used as a reflecting surface, and the radio wave radiated to the communication area set around the vehicle body is transmitted. It is only necessary to provide a structure that reflects the radio wave radiated from the antenna toward the outer peripheral surface of the vehicle body toward the communication area in a manner that increases the strength.
(Appendix)
Next, a technical idea that can be grasped from the above embodiment and its modifications will be additionally described.

  (A) In the vehicular antenna device according to any one of claims 1 to 3, the dipole antenna has two elements constituting the antenna bent into a V-shape on the vehicle body side. A vehicle antenna device characterized by comprising: According to this configuration, the directivity of the dipole antenna can be increased in the direction along the outer peripheral surface of the vehicle body as compared with the case where two elements are arranged so as to be parallel to the outer peripheral surface of the vehicle body. The communication area can be expanded in the direction along the outer peripheral surface of the vehicle body.

  (B) In the vehicular antenna device according to any one of claims 1 to 3, the antenna is a folded dipole antenna having a structure in which tip portions of the two elements are connected to each other by the element. A vehicle antenna device. It has been confirmed by the inventors that the shorter the distance from the antenna to the reflecting surface, the smaller the impedance of the antenna, making it difficult to match the impedance between the antenna and its feeder. In this regard, as described above, if a so-called folded dipole antenna is used as an antenna that radiates radio waves in the UHF band, the impedance of the antenna can be increased, so the distance from the antenna to the reflecting surface is shortened. Even if this is the case, impedance matching between the antenna and its feed line is facilitated.

  L: Distance, S: Communication area, A1, A2, A3, A4 ... Antenna device, GP ... Gap, 10 ... In-vehicle device, 11, 22, 81 ... Transmitter, 11a ... Feed line, 12, 21, 82 ... Receive Device: 13 ... Wireless power transmission device, 14, 83 ... Vehicle control device, 15 ... Control target, 20, 90 ... Portable device, 23 ... Portable device control device, 24 ... Rectifier device, 25 ... Power supply device, 30 ... Door handle Device 31 ... Door handle 31a ... Grip part 32 ... Operating part 33 ... Rotating part 40 ... Outer panel 41 ... Groove part 42 ... Support member 50 ... Dipole antenna 51, 52, 61, 62, 71 73 elements, 53 feeding points, 60 V dipole antennas, 70 folded dipole antennas, 80 vehicles.

Claims (6)

A vehicle antenna device comprising an antenna provided on a vehicle body, and radiating UHF band radio waves toward a communication area set around the vehicle body through the antenna,
A gap is formed between the outer peripheral surface of the vehicle body and the antenna, and the outer peripheral surface of the vehicle body disposed opposite to the antenna with the gap is used as a reflection surface to radiate to the communication area. A vehicle antenna comprising: a radio wave reflection structure that reflects radio waves radiated from the antenna toward the outer peripheral surface of the vehicle body toward the communication area in a manner that enhances the strength of the radio radio waves generated. apparatus. The antenna is disposed along the outer peripheral surface of the vehicle body, and a recess is formed in a portion of the vehicle body facing the antenna so as to form the gap. The vehicular antenna device according to claim 1, comprising an inner wall surface of the recess facing the antenna. The communication area set around the vehicle body is a semicircular communication area set around the vehicle door, and the antenna is disposed inside a door handle provided on the vehicle door. The vehicular antenna apparatus according to claim 2, wherein the concave portion includes a groove portion recessed in an outer peripheral surface of the vehicle door as a portion into which a user inserts a hand when holding the door handle. The vehicle antenna device according to claim 3, wherein the antenna is a dipole antenna including two elements disposed so as to be parallel to an outer peripheral surface of the vehicle body. When the wavelength of the radio wave is “λ”, the length of the two elements is set to a length of “λ / 4”, and the distance from the dipole antenna to the reflecting surface is L. The vehicle antenna device according to claim 4, wherein the relationship of “5 mm ≦ L ≦ λ / 4” is satisfied. The vehicle antenna device according to claim 5, wherein a distance L from the dipole antenna to the reflecting surface is set to a length of “λ / 4”.

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