JP4904302B2 - Automotive antenna and composite antenna - Google Patents

Description

  The present invention relates to an in-vehicle antenna and a composite antenna whose horizontal directivity is suitably controlled.

  Conventionally, as a vehicle-mounted antenna, a GPS antenna is used by being installed on an instrument panel (hereinafter referred to as an instrument panel) in a vehicle interior. On the other hand, in recent years, the need for wireless communication in the passenger compartment has also increased. For example, there is a need to use a wireless hands-free device for using a mobile phone while driving. There is also a growing need for wireless data communication in a vehicle interior using a personal computer (hereinafter referred to as a personal computer) or various mobile devices. For these wireless communications, for example, inverted F type and monopole type antennas are used.

  In-vehicle wireless communication antennas are required to have good radiation characteristics in the horizontal direction. Also, as the installation location of the in-vehicle wireless communication antenna, the front of the passenger compartment (for example, the instrument panel) or the rear of the passenger compartment (for example, the rear tray) is usually selected. Therefore, radiation characteristics in the direction from the front of the vehicle compartment or the rear of the vehicle compartment to the center of the vehicle compartment are particularly required. In order to improve the directivity of the antenna, a technique for installing a parasitic element in the vicinity of the antenna element has been known so far (Patent Documents 1 to 4), thereby improving the radiation characteristics in a specific direction. Is possible.

In-vehicle antennas have a strong need for miniaturization as much as possible from the viewpoints of installation space and scenery in the passenger compartment. When an inverted-F antenna is used as an in-vehicle wireless communication antenna, a conductor pattern can be formed on a substrate by etching or the like. Thus, by arranging the antenna elements on a plane, an in-vehicle wireless communication antenna having a small thickness and not bulky can be provided.
Japanese Patent Laid-Open No. 2-113706 JP-A-6-69716 Japanese Patent Laid-Open No. 11-274845 JP 2002-223107 A

  However, in the conventional method in which a parasitic element is installed in the vicinity of the antenna element in order to improve the directivity of the antenna, the parasitic element is disposed at a position spatially opposed to the antenna element. That is, antenna characteristics in a specific direction are improved by arranging parasitic elements in a three-dimensional manner. Therefore, there was a problem that the volume of the antenna is bulky and the installation space becomes large. Further, since it is necessary to separately manufacture the antenna element and the parasitic element and to assemble them while adjusting the relative positional relationship, there is a problem that the manufacturing of the antenna becomes expensive.

  Accordingly, the present invention has been made to solve the above problems, and an object thereof is to provide a low-cost vehicle-mounted antenna and a composite antenna in which horizontal directivity is suitably controlled and installation space is small. .

According to a first aspect of the vehicle-mounted antenna of the present invention, a grounding conductor, a linear radiation conductor disposed in parallel with one side of the grounding conductor, one end of the radiation conductor and the grounding conductor are orthogonal to each other. An antenna having a grounding part to be connected, a power feeding part that feeds power to the radiation conductor, and performing a monopole operation, a first element part disposed close to and parallel to the radiation conductor, and the first element And a second element part for connecting the one end of the part and the ground conductor in a direction orthogonal to each other, and the open end of the first element part is disposed so as to be opposite to the open end of the radiation conductor. A parasitic element, and an open end of the radiation conductor is disposed so as to be close to a bent portion of the parasitic element formed by the first element part and the second element part , and At least half the length of the range from the open end of the radiating conductor to the power supply unit Characterized in that it is surrounded by the passive element.

  Another aspect of the vehicle-mounted antenna of the present invention is characterized in that the parasitic element is arranged so that a gain of the antenna that performs the monopole operation has a peak in a direction orthogonal to the radiation conductor. And

  Another aspect of the vehicle-mounted antenna of the present invention is characterized in that the antenna that performs the monopole operation, the ground conductor, and the parasitic element are arranged on the same plane.

  Another aspect of the vehicle-mounted antenna of the present invention is characterized in that the antenna that performs the monopole operation, the ground conductor, and the parasitic element are patterned on the same substrate.

Another aspect of the vehicle-mounted antenna of the present invention is characterized in that the antenna that performs the monopole operation is a wireless hands-free device for a mobile phone in a vehicle interior or an antenna used for wireless data communication .

  According to a first aspect of the composite antenna of the present invention, any one of the above-described vehicle-mounted antennas and a second antenna having a second directivity different from the directivity of the vehicle-mounted antenna are arranged on the same plane. It is characterized by being.

  According to the present invention, by providing a parasitic element on the same plane as an antenna element, a directivity in the horizontal direction is suitably controlled, and a low-cost vehicle-mounted antenna and a composite antenna having a small installation space are provided. Can do.

  A vehicle-mounted antenna and a composite antenna according to a preferred embodiment of the present invention will be described in detail with reference to the drawings. In addition, about each structural part which has the same function, the same code | symbol is attached | subjected and shown for simplification of illustration and description.

  A vehicle-mounted antenna according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 shows a plan view of a vehicle-mounted antenna 100 according to this embodiment. The vehicle-mounted antenna 100 of the present embodiment includes a ground conductor 110, an inverted F antenna 120 that operates as a monopole antenna, and a parasitic element 130, which are formed on a substrate 140. Hereinafter, an inverted F antenna will be described as an example of the monopole antenna.

  In order to simplify the following description, the coordinate system (X axis, Y axis, Z axis) shown in FIG. 1 is used. Here, when the vehicle-mounted antenna 100 is on the XY plane, and the vehicle-mounted antenna 100 is installed in front of the vehicle (for example, an instrument panel), the passenger compartment direction is the X-axis direction and the driver seat direction is the Y-axis direction. The Z-axis direction is a vehicle height direction perpendicular to the XY plane.

  The inverted F antenna 120 includes a linear radiating conductor 121 arranged in parallel to one side 110 a of the ground conductor 110, and a grounding part 122 connected to one side 110 a of the ground conductor 110 in a direction perpendicular to one end 121 a of the radiating conductor 121. The power supply unit 123 is disposed in the vicinity of the grounding unit 122 and supplies power to the radiation conductor 121.

  The parasitic element 130 includes a first element part 131 and a second element part 132, which are connected at right angles at one end to form a bent part 133. The first element portion 131 is disposed close to and parallel to the radiation conductor 121, and the other end of the second element portion 132 is connected to the ground conductor 110.

  In the in-vehicle antenna 100 of the present embodiment, the inverted F antenna 120 and the parasitic element 130 configured as described above are arranged so that the open ends thereof face each other. That is, the open end 121b of the radiation conductor 121 is disposed so as to face left in FIG. 1, and the open end 131b of the first element portion 131 is disposed so as to face right in FIG. Note that the radiating conductor 121 may be arranged so that the open end 121b faces right and the open end 131b of the first element portion 131 faces left.

  Furthermore, in the vehicle-mounted antenna 100, the open end 121b of the radiating conductor 121 and the bent portion 133 of the parasitic element 130 are placed close to each other, and the open end 121b of the radiating conductor 121 is positioned inside the bent portion 133. Yes. Thereby, the parasitic element 130 is disposed so as to surround at least the open end 121b side of the inverted F antenna 120.

  By arranging the parasitic element 130 with respect to the inverted F antenna 120 as described above, the directivity of the inverted F antenna 120 can be improved in the vehicle-mounted antenna 100 of the present embodiment. Below, in order to compare with the radiation characteristic of the vehicle-mounted antenna 100 of this embodiment, the radiation characteristic of the conventional reverse F antenna which does not have the parasitic element 130 is demonstrated first.

  A configuration of a conventional inverted F antenna 200 having no parasitic element 130 is shown in the plan view of FIG. The inverted F antenna 200 has the same configuration as the in-vehicle antenna 100 of the present embodiment except that the parasitic element 130 is not provided. Here, the same coordinate system used in FIG. 1 is used. The radiation characteristics of the conventional inverted F antenna 200 will be described below with reference to FIG. In FIG. 3, as radiation characteristics of the inverted F antenna 200, respective radiation patterns on the XY plane, the ZX plane, and the YZ plane are denoted by reference numerals 11 to 13. Further, by adding H or V after each symbol, the horizontal component and the vertical component of each radiation pattern are shown.

  From FIG. 3, it can be seen that the radiation pattern of the inverted F antenna 200 has a high gain on the XY plane and a low directivity in the Z-axis direction. Further, the highest gain on the XY plane is a direction rotated 60 ° from the X-axis direction (vehicle compartment direction) (60 ° on the passenger seat side from the vehicle compartment direction). As a vehicle-mounted antenna used for in-vehicle wireless communication or the like, it is desirable that a gain peak be obtained in the X-axis direction, and the conventional inverted F antenna 200 cannot obtain a suitable radiation characteristic.

  On the other hand, in the vehicle-mounted antenna 100 of the present embodiment, by providing the parasitic element 130, the gain peak on the XY plane can be improved so as to be in the desired X-axis direction. The radiation pattern of the vehicle-mounted antenna 100 is shown in FIG. Similarly to FIG. 3, the respective radiation patterns in the XY plane, the ZX plane, and the YZ plane are denoted by reference numerals 21 to 23. As seen in the radiation pattern 21H shown in FIG. 4A, the gain peak in the XY plane is improved so as to be substantially in the X-axis direction.

  As described above, in the vehicle-mounted antenna 100 according to the present embodiment, the parasitic element 130 is provided in the vicinity of the inverted F antenna 120, whereby the horizontal (XY plane) radiation pattern is obtained and the gain peak is in the vehicle compartment direction. It is possible to improve so that. Thereby, the vehicle-mounted antenna suitable for in-vehicle wireless communication etc. can be provided.

  In the vehicle-mounted antenna 100 according to the present embodiment, the open end 131b of the first element portion 131 faces the open end 121b of the radiating conductor 121, and the bent portion 133 does not surround the open end 121b of the radiating conductor 121. The power feeding element 130 was disposed. As another arrangement method of the parasitic element 131, for example, the open end 131 b of the first element portion 131 and the open end 121 b of the radiation conductor 121 are in the same direction, and the second element portion 132 is close to the ground portion 122. It is also possible to arrange them in A configuration example of the comparative antenna in which the parasitic elements are arranged in this way is shown in the plan view of FIG.

  In the comparative antenna 300 shown in FIG. 5, the parasitic element 330 is disposed so as to surround the inverted F antenna 120 from the ground portion 122 side. FIG. 6 shows a radiation pattern of the comparative antenna 300 configured as described above. Also in the figure, as in FIGS. 3 and 4, the radiation patterns in the XY plane, the ZX plane, and the YZ plane are denoted by reference numerals 31 to 33. The radiation pattern 31H shown in FIG. 6A is hardly improved from the radiation pattern 11H shown in FIG. 3A, and the gain peak in the XY plane is rotated by about −60 ° from the X-axis direction. It has become. That is, when the parasitic element 330 is disposed so as to surround the inverted F antenna 120 from the grounding part 122 side, the desired gain in the X-axis direction cannot be improved.

As described above, in the in-vehicle antenna 100 of the present embodiment, the parasitic element 130 is disposed so as to surround the inverted F antenna 120 from the open end 121b side of the radiating conductor 121, so that the gain peak on the horizontal plane is increased. It is possible to improve the room direction.
Further, if the antenna operates as a monopole antenna, the same effect can be obtained not only when the inverted F antenna is used but also when a normal monopole antenna is used.

  As a configuration of the vehicle-mounted antenna 100, it is preferable that the first element portion 131 is disposed adjacent to at least half of the range from the open end 121b of the radiation conductor 121 to the power feeding portion 123. In the vehicle-mounted antenna 100, the ground conductor 110, the inverted F antenna 120, and the parasitic element 130 are disposed on the same plane substrate 140. Therefore, these can be formed as a pattern on the substrate 140 using an etching method or the like. Therefore, the vehicle-mounted antenna of this embodiment can be manufactured at low cost.

  According to the present invention, by forming a parasitic element on the same plane as the antenna element, it is possible to provide a low-cost vehicle-mounted antenna with a small installation space in which horizontal directivity is suitably controlled.

  An embodiment of the composite antenna of the present invention will be described with reference to FIG. FIG. 7 is a plan view showing an example of the composite antenna of the present embodiment. In the composite antenna 400 of the present embodiment, an inverted F antenna 410 that operates as a monopole antenna and a second antenna 420 having a second directivity different from the directivity of the inverted F antenna 410 are arranged on the same plane. Has been configured. Here, the circuit board 430 for the second antenna 420 is arranged between the inverted F antenna 410 and the second antenna 420, but the circuit board 430 is not necessarily arranged in this way.

  Also in the composite antenna 400 of this embodiment, the parasitic element 411 is disposed in order to improve the directivity of the inverted F antenna 410 that performs monopole operation. Thereby, even when the composite antenna 400 is configured by integrating with the second antenna 420 having different directivities, the directivity of the inverted F antenna 410 can be preferably improved. As the second antenna 420, for example, a GPS antenna having directivity in the zenith direction can be used, and this can be combined with a monopole antenna to form a composite antenna.

  Note that the description in the present embodiment shows an example of the vehicle-mounted antenna and the composite antenna according to the present invention, and the present invention is not limited to this. The detailed configuration and detailed operation of the vehicle-mounted antenna and the like in the present embodiment can be changed as appropriate without departing from the spirit of the present invention.

It is a top view of the vehicle-mounted antenna which concerns on embodiment of this invention. It is a top view of the conventional vehicle-mounted antenna. It is a figure which shows the radiation characteristic of the conventional vehicle-mounted antenna. It is a figure which shows the radiation characteristic of the vehicle-mounted antenna of this embodiment. It is a top view of the antenna for a comparison. It is a figure which shows the radiation characteristic of the antenna for a comparison. It is a top view of the compound antenna concerning the embodiment of the present invention.

Explanation of symbols

100, 200, 300 Car-mounted antenna 110 Grounding conductor 120, 410 Reverse F antenna 121 Radiation conductor 122 Grounding part 123 Feeding part 130, 330, 411 Parasitic element 131 First element part 132 Second element part 133 Bending part 140 Substrate 400 Composite antenna 420 Second antenna 430 Circuit board

Claims (6)

A ground conductor;
A linear radiating conductor disposed in parallel with one side of the ground conductor, a grounding portion for connecting one end of the radiating conductor and the grounding conductor in a direction orthogonal to each other, and a feeding portion for feeding power to the radiating conductor. An antenna that has a monopole operation, and
A first element portion disposed close to and parallel to the radiation conductor; a second element portion that connects one end of the first element portion and the ground conductor in a direction orthogonal to the first element portion; A parasitic element arranged so that the open end of the element portion is opposite to the open end of the radiation conductor,
The open end of the radiating conductor is disposed so as to be close to a bent portion of the parasitic element formed by the first element portion and the second element portion , and the feeding from the open end of the radiating conductor. A vehicle-mounted antenna, wherein at least half the length of the range up to the portion is surrounded by the parasitic element . The in-vehicle antenna according to claim 1, wherein the parasitic element is arranged so that a gain of the antenna performing the monopole operation has a peak in a direction orthogonal to the radiation conductor. The in-vehicle antenna according to claim 1 or 2, wherein the antenna that performs the monopole operation, the ground conductor, and the parasitic element are arranged on the same plane. 4. The vehicle-mounted device according to claim 1, wherein the antenna that performs the monopole operation, the ground conductor, and the parasitic element are formed in a pattern on the same substrate. 5. antenna. 5. The vehicle-mounted vehicle according to claim 1, wherein the antenna that performs the monopole operation is a wireless hands-free device for a mobile phone in a vehicle interior or an antenna used for wireless data communication. antenna. The vehicle-mounted antenna according to any one of claims 1 to 5 and a second antenna having a second directivity different from the directivity of the vehicle-mounted antenna are arranged on the same plane. A composite antenna characterized by

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