JP2006014154A - Antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antenna which is capable of excellently communicating with the outside of a vehicle by suppressing a radio wave from being attenuated by shielding a direct wave propagation path, and by being non-directional on a horizontal plane. <P>SOLUTION: In an antenna mounted inside a vehicle, two antenna elements 12 and 13 provided in parallel to a floor surface of the vehicle are disposed to be orthogonal with each other. Thus, since radio waves are radiated toward windows and further multiple reflection occurs inside the vehicle, radio waves to be radiated from the windows can be increased. Moreover, the antenna is non-directional on a horizontal plane, thereby excellently performing communication in any direction regardless of the direction of the vehicle to a base station outside the vehicle. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an antenna, and more particularly to an antenna mounted in a vehicle.

  In recent years, there has been a movement to provide a car navigation device with a communication function with the outside of the vehicle. Since the wireless LAN usable area that provides an Internet connection service by wireless LAN to an unspecified number of users is rapidly increasing, it is considered to use the wireless LAN as a communication means of a car navigation apparatus. Yes. Since the wireless LAN has a mechanism for switching the transmission speed in accordance with the received power, high sensitivity is required to maintain high-speed communication.

  As such a wireless LAN antenna, a PC-mounted wireless LAN terminal for indoor communication is known. These wireless LAN terminals generally have a vertical polarization main body.

  Further, there is a technique of an antenna-integrated receiver in which a planar antenna is disposed on the upper part of a case of an in-vehicle receiver and directivity is directed in the front-rear direction and the upward direction along the vehicle traveling direction. (For example, refer to Patent Document 1).

In addition, there is a technique for improving in-vehicle wireless communication by disposing a dipole antenna in a vertical direction and a horizontal direction on a dashboard of a vehicle and adopting polarization diversity. (For example, refer to Patent Document 2).
JP-A-6-237188 JP 2003-60543 A

  However, when the wireless LAN terminal as described above is mounted at a car navigation mounting position such as in the instrument panel, the direct wave propagation path outside the vehicle is shielded by the vehicle body as shown in FIG. A problem arises in that the communication speed with the base station outside the vehicle decreases due to attenuation.

  By the way, in a moving body such as a vehicle, it is desired to use an omnidirectional antenna because the direction with respect to the base station outside the vehicle changes according to the parking position and direction. However, the antenna described in Patent Document 1 has a problem in that the electric field strength decreases when an out-vehicle base station exists in the left-right direction of the vehicle.

  In addition, the antenna described in Patent Document 2 has a problem that the directivity is weakened on a horizontal plane, and the electric field strength decreases when an out-of-vehicle base station exists in that direction.

  In view of the above points, the present invention suppresses the attenuation of radio waves by shielding the propagation path of a direct wave, and at the same time, makes it possible to satisfactorily communicate with the outside of the vehicle by using a horizontal plane non-directional directivity. An object is to provide an antenna that can be used.

  In order to achieve the above object, according to the first aspect of the present invention, there are two antenna elements (12, 13) which are antennas mounted in a vehicle and arranged so as to be orthogonal to each other on the substrate (1). ) And the two antenna elements (12, 13) are arranged in parallel to the vehicle floor.

  Thus, by mounting the antenna elements (12, 13) in parallel to the vehicle floor surface, it is possible to increase the radio wave propagating from the window to the outside of the vehicle by directing the radio wave radiation direction toward the window. Furthermore, since multiple reflection occurs in the vehicle, the radio wave radiated from the window can be increased.

  Further, the antenna elements (12, 13) are arranged in a direction orthogonal to each other so that the horizontal plane is non-directional, and communication can be improved in any direction regardless of the direction of the vehicle relative to the base station outside the vehicle. it can.

  In addition, as in the invention described in claim 2, by forming the two antenna elements (12, 13) in an L shape, space saving on the substrate can be achieved.

  Further, as in the invention described in claim 3, by forming the two antenna elements (12, 13) in an F-shape, space can be saved on the substrate. Since the impedance can be matched at the (12, 13) portion, the matching circuit (14, 15) becomes unnecessary.

  Further, as in the invention described in claim 4, the two antenna elements (12, 13) are formed of different members by forming the two antenna elements (12, 13) as a pattern on the substrate. This eliminates the need for cost savings.

  Further, the invention according to claim 5 is characterized in that the antenna is arranged on a substrate in the communication device (20) mounted in the instrument panel in the vehicle. Thereby, the appearance can be improved, and further, space saving and cost saving can be achieved.

  In the invention described in claim 6, the first substrate (1a) provided with the two antenna elements (12, 13), and the second substrate (1b) provided with the signal processing circuit unit, The first substrate (1a) is connected to the second substrate (1b) so that the angle can be changed. Thereby, the two antenna elements (12, 13) can always be maintained parallel to the vehicle floor surface regardless of the mounting angle of the signal processing circuit unit.

  In the invention according to claim 7, a first substrate (1a) provided with two antenna elements (12, 13), and a second substrate (1b) provided with a signal processing circuit unit, And the first substrate (1a) and the second substrate (1b) are arranged at a predetermined interval. Thereby, two antenna elements (12, 13) can be arranged in a place with good radio wave sensitivity regardless of the place where the signal processing circuit unit is mounted. Furthermore, two antenna elements (12, 13) can be arranged in parallel to the vehicle floor regardless of the mounting angle of the signal processing circuit section.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. The antenna of this 1st Embodiment is used as an antenna of the vehicle equipment (car navigation apparatus etc.) arrange | positioned in the vehicle which communicates between base stations outside a vehicle. FIG. 1 is a perspective view showing the mounting position of the antenna according to the first embodiment in the passenger compartment. As shown in FIG. 1, the antenna 100 according to the first embodiment is parallel to the vehicle floor surface in the instrument panel where the direct wave propagation path is shielded by the vehicle body. It is installed.

  The configuration of the antenna according to the first embodiment will be described. FIG. 2 is a perspective view showing the antenna of the first embodiment. As shown in FIG. 2, the antenna 100 according to the first embodiment includes a substrate 1. The substrate 1 is covered with a case 30 indicated by a broken line in FIG.

  The substrate 1 is provided with a ground pattern portion 10 and a non-ground pattern portion 11. Two antenna elements 12 and 13 are arranged in the non-ground pattern portion 11. The ground pattern section 10 includes matching circuits 14 and 15 that adjust impedance, microstrip lines 16 and 17, an RF circuit section 18 that modulates and demodulates an RF signal, and a radio signal that is input to and output from the RF circuit section 18. A baseband circuit unit 19 that performs baseband processing according to the method is formed. The signal processing circuit unit of the present invention includes an RF circuit unit 18 and a baseband circuit unit 19.

  The two antenna elements 12 and 13 are formed as a pattern on the substrate 1 and arranged in directions orthogonal to each other. The antenna elements 12 and 13 are connected to matching circuits 14 and 15, respectively, and the connection point is a feeding point. The matching circuits 14 and 15 are connected to the RF circuit unit 18 via the microstrip lines 16 and 17.

  Next, the effect when the antenna of the first embodiment is used will be described with reference to FIGS. FIG. 3 is a schematic diagram showing radio wave propagation of the antenna according to the first embodiment, and corresponds to FIG. 10 described in the section of the prior art. FIG. 4A is a characteristic diagram showing the directivity in the horizontal plane of the antenna of the first embodiment, and FIG. 4B is a characteristic diagram showing the directivity in the horizontal plane of the prior art in which the monopole antennas are arranged vertically. It is. 4 (a) and 4 (b) show the results of measurement at a distance of 20 m using an antenna with a frequency of 2.4 GHz.

  In the above configuration, the antenna elements 12 and 13 are arranged in parallel to the vehicle floor surface by mounting the antenna 100 in parallel to the vehicle floor surface. As a result, as shown in FIG. 3, the radio wave propagating from the window to the outside of the passenger compartment can be increased by directing the radiation direction of the radio wave toward the window. At the same time, the radio waves cause multiple reflections in the passenger compartment, so that the radio waves propagating from the window to the outside of the passenger compartment can be further increased. As described above, even when the antenna 100 is arranged at a position where the direct wave propagation path is shielded by the vehicle body, it is possible to improve communication.

  Moreover, as shown in FIG. 4A, the directivity in all horizontal directions can be improved by making the arrangement pattern of the two antenna elements 12 and 13 orthogonal. Thereby, it can be set as a directivity of omnidirectional horizontal plane, it becomes possible to improve communication in any direction regardless of the direction of the vehicle with respect to the base station outside the vehicle, and can be suitably used as an antenna of a moving body. .

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. The second embodiment differs from the first embodiment in the shape of the antenna elements 12 and 13. The same parts as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  FIG. 5 is a perspective view showing the antenna of the second embodiment. In FIG. 5, only the antenna elements 12 and 13 are shown. As shown in FIG. 5, in the second embodiment, L-shaped antenna elements 12 and 13 in which the tips of the antenna elements 12 and 13 are bent 90 degrees in a horizontal plane are provided, and the L-shaped antenna elements 12 and 13 are provided. Are arranged so as to be orthogonal to each other. By adopting such a configuration, it is possible to save the space of the portion where the antenna elements 12 and 13 are arranged on the substrate 1.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIG. The third embodiment is different from the first embodiment in the shape of the antenna elements 12 and 13. The same parts as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  FIG. 6 is a perspective view showing the antenna of the third embodiment. In FIG. 6, only the antenna elements 12 and 13 are shown. As shown in FIG. 6, in the third embodiment, the F-shaped antenna elements 12 and 13 in which the tips of the antenna elements 12 and 13 are bent 90 degrees in a horizontal plane and the feeding point or the ground is connected to the bent portions. The F-shaped arrangement patterns of the antenna elements 12 and 13 are arranged so as to be orthogonal to each other. By adopting such a configuration, it is possible to save the space of the portion where the antenna elements 12 and 13 are arranged on the substrate 1. Furthermore, according to the configuration of the third embodiment, the impedance can be matched in the antenna elements 12 and 13, so that the matching circuit can be eliminated.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described with reference to FIG. Compared to the first embodiment, the fourth embodiment includes an antenna including an antenna element, a matching circuit, a microstrip line, an RF circuit unit, and a baseband circuit unit. It is different in that it is arranged on a substrate in a car navigation device (communication device) 20 mounted in the panel. The same parts as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  FIG. 7 is a perspective view showing the mounting position of the antenna of the fourth embodiment in the vehicle interior. In FIG. 7, the car navigation device 20 is drawn with a solid line, but it is actually in the instrument panel, and can be seen from outside except the front where the display is. As shown in FIG. 7, in the fourth embodiment, the two antenna elements 12 and 13 are arranged in parallel to the substrate and arranged in directions orthogonal to each other. And the board | substrate is arrange | positioned in the car navigation apparatus 20 so that it may become parallel with respect to a vehicle floor surface.

  Thus, by arranging the antenna in the communication device 20, the antenna elements 12 and 13 can be made invisible from the outside, so that the appearance can be improved. Furthermore, since the antenna is integrated with the communication device 20, space saving and cost saving can be achieved.

(Fifth embodiment)
Next, a fifth embodiment of the present invention will be described with reference to FIG. In the fifth embodiment, the antenna elements 12 and 13 and the signal processing circuit unit are formed on different substrates as compared with the first embodiment, and the angle of one substrate can be changed with respect to the other substrate. The point of being connected to is different. The same parts as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  FIG. 8 is a perspective view showing the configuration and arrangement state of the antenna of the fifth embodiment. As shown in FIG. 8, in the fifth embodiment, the first substrate 1a on which the antenna elements 12 and 13 and the matching circuits 14 and 15 are mounted, the microstrip lines 16 and 17, the RF circuit unit 18 and the baseband. The second substrate 1b on which the circuit unit 19 is mounted is separated into two substrates. The matching circuits 14 and 15 mounted on the first substrate 1a and the microstrip lines 16 and 17 mounted on the second substrate 1b are connected by signal lines. The first substrate 1a and the second substrate 1b are connected to each other so that the angle can be adjusted with a joint portion (hinge portion) as a rotation axis. The second substrate 1b is provided perpendicular to the vehicle floor surface, and the angle of the first substrate 1a is adjusted so as to be parallel to the vehicle floor surface.

  By adopting such a configuration, the angle between the two board surfaces can be adjusted, and the antenna elements 12 and 13 are always attached to the vehicle floor surface regardless of the mounting angle of the board on which the signal processing circuit unit is mounted. It becomes possible to maintain it parallel to.

(Sixth embodiment)
Next, a sixth embodiment of the present invention will be described with reference to FIG. The sixth embodiment is different from the first embodiment in that the antenna elements 12 and 13 and the signal processing circuit section are separated from each other by a predetermined interval. The same parts as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  FIG. 9 is a perspective view showing the antenna of the sixth embodiment. As shown in FIG. 9, in the sixth embodiment, the first substrate 1a on which the antenna elements 12, 13 and the matching circuits 14, 15 are mounted, the microstrip lines 16, 17, the RF circuit unit 18, and the baseband. The second substrate 1b on which the circuit unit 19 is mounted is separated into two substrates. The matching circuits 14 and 15 mounted on the first substrate 1a and the microstrip lines 16 and 17 mounted on the second substrate 1b can be connected by connectors 21 and 22, respectively.

  By adopting such a configuration, the antenna elements 12 and 13 are arranged in places with good radio wave sensitivity regardless of the mounting location of the substrate on which the signal processing circuit section including the RF circuit section 18 and the baseband circuit section 19 is mounted. It becomes possible to do. Furthermore, the antenna elements 12 and 13 can be arranged in parallel to the vehicle floor regardless of the mounting angle of the substrate on which the signal processing circuit unit is mounted.

It is a perspective view which shows the mounting position in the vehicle interior of the antenna of 1st Embodiment. It is a perspective view which shows the antenna of 1st Embodiment. It is the schematic which shows the electromagnetic wave propagation state of the antenna of 1st Embodiment. (A) is a characteristic diagram which shows the directivity in the horizontal surface of the antenna of 1st Embodiment, (b) is a characteristic diagram which shows the directivity in the horizontal surface of the conventional antenna. It is a perspective view which shows the antenna of 2nd Embodiment. It is a perspective view which shows the antenna of 3rd Embodiment. It is a perspective view which shows the mounting position in the vehicle interior of the antenna of 4th Embodiment. It is a perspective view which shows the structure of the antenna of 5th Embodiment, and its arrangement | positioning state. It is a perspective view which shows the antenna of 6th Embodiment. It is the schematic which shows the electromagnetic wave propagation state of the conventional antenna.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Board | substrate, 10 ... Ground pattern part, 11 ... Non-ground pattern part, 12, 13 ... Antenna element, 14, 15 ... Matching circuit, 16, 17 ... Microstrip line, 18 ... RF circuit part, 19 ... Baseband circuit 100, antenna.

Claims (7)

An antenna mounted in a vehicle, comprising two antenna elements (12, 13) arranged orthogonal to each other on a substrate (1), wherein the two antenna elements (12, 13) are An antenna characterized by being arranged in parallel to a vehicle floor. The antenna according to claim 1, wherein the two antenna elements (12, 13) are each formed in an L shape. The antenna according to claim 1, wherein the two antenna elements (12, 13) are each formed in an F shape. The antenna according to any one of claims 1 to 3, wherein the two antenna elements (12, 13) are formed as a wiring pattern on the substrate (1). The antenna according to any one of claims 1 to 4, wherein the substrate (1) is arranged in a communication device (20) mounted in an instrument panel in a vehicle. A first substrate (1a) on which the two antenna elements (12, 13) are provided; and a second substrate (1b) on which a signal processing circuit unit is provided, the first substrate (1a) Is connected to the second substrate (1b) so that the angle thereof can be adjusted. A first substrate (1a) on which the two antenna elements (12, 13) are provided; and a second substrate (1b) on which a signal processing circuit unit is provided, the first substrate (1a) 5) and the second substrate (1b) are spaced apart from each other by a predetermined distance.

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