JP2012175210A - Vehicle antenna device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle antenna device which realizes directivity corresponding to various diversity systems in the same antenna configuration and can have high reception sensitivity performance.SOLUTION: In a vehicle antenna device, a first antenna 101 and a second antenna 102 are made of conductive material and are respectively pasted on a rear window pane 108 along right and left sides of the rear window pane 108. A first ground wire 109 and a second ground wire 110 are respectively arranged perpendicularly to the first antenna 101 and the second antenna 102 from vicinity of the first antenna 101 and the second antenna 102. A short circuit point between the first ground wire 109 or the second ground wire 110 and a ground of a vehicle 100 is switched by high frequency switches 111 and 112, according to a diversity system.

Description

  The present invention relates to a vehicle antenna device that is compatible with a plurality of diversity systems and is mounted on a window glass of a vehicle.

  In recent years, vehicles are equipped with various communication systems (for example, AM / FM broadcasting, digital terrestrial broadcasting, GPS, VICS, ETC, etc.), and a large number of antennas corresponding to these communications are required. In some cases, the antenna is attached to a fixed rear or front window glass.

  As a specific example of the antenna mounted on such a rear window glass, an antifogging heater including a plurality of conductive wires provided on the window glass, a first antenna element disposed on the window glass above the heater, and a first antenna element A device including two antenna elements, a first feeding point for the first antenna element arranged on the left side of the window glass, and a second feeding point for the second antenna element arranged on the right side of the window glass. It is known (see, for example, Patent Document 1).

  In the device described in Patent Document 1, the positions of the feeding points of the first and second antenna elements are separated from each other, and the first antenna element and the second antenna element have basically different directivity characteristics. Their directivity characteristics can complement each other.

  Also, by using the antenna conductor 3 as a monopole antenna and feeding power from one bus bar and the other bus bar, a U-shaped defogger is used as a dipole antenna, and the antenna conductor 3 and the defogger receive signal There is known one that selectively uses a received signal having a higher receiving sensitivity (see, for example, Patent Document 2).

JP 2004-520737 A JP 7-336124 A

  However, the configurations described in Patent Documents 1 and 2 are suitable for adopting the antenna switching diversity method because the directivity of each antenna is different, but are not suitable for the phase diversity method that requires the same directivity. In order to cope with the phase diversity method, the antenna element configuration needs to be significantly changed, and the manufacturing cost increases.

  Further, in a multipath environment such as an urban area, the phase diversity method is more advantageous than the antenna switching diversity method, and thus high reception sensitivity performance may not be ensured.

  The present invention has been made in view of the above-described circumstances, and the object thereof is to realize a cost reduction by being able to be realized with the same antenna configuration regardless of the diversity method, and to provide an antenna according to the diversity method according to the propagation environment. By realizing this, an object is to provide a vehicle rear window glass-mounted antenna that ensures high reception sensitivity performance.

  In order to achieve the above object, the present invention provides a vehicle antenna device that is mounted on a vehicle and is connected to a receiving device that demodulates radio waves in at least one of an antenna switching diversity method and a phase diversity method. A first antenna provided on the window glass at a predetermined interval along one short side of the window glass, and the other facing the first antenna on the window glass The second antenna provided at a predetermined distance from the window glass along the short side of the window, the power feeding part of the first antenna and the power feeding part of the second antenna are diagonal to the window glass. Provided in the vicinity of the feeding portion of the first antenna and along one long side of the window glass at an angle of 90 degrees with respect to the first antenna. A first ground wire and a second wire provided in proximity to the feeding portion of the second antenna and along the other long side of the window glass at an angle of 90 degrees with respect to the second antenna. 2 ground lines, a first switching unit connected to the first ground line and switching the connection between the first ground line and the ground to high frequency connection or disconnection, and the second ground line And a second switching unit that is connected and switches the connection between the second ground line and the ground to high frequency connection or non-connection.

  According to the vehicular antenna apparatus of the present invention, since the same antenna configuration corresponding to a plurality of diversity systems is used, the manufacturing cost is low, and the diversity system and the antenna directivity can be controlled according to the propagation environment. Sensitivity performance can be demonstrated.

The figure which shows the vehicle window glass mounting antenna apparatus in the 1st Embodiment of this invention. The figure which shows the vehicle carrying the vehicle window glass mounting antenna apparatus in embodiment of this invention. It is a figure which shows the directivity of the vehicle window glass mounting antenna apparatus in embodiment of this invention, Comprising: (a) is a case where the 1st terminal (4th terminal) and the 2nd terminal (5th terminal) are connected. (B) which shows the directivity of this figure is a figure which shows the directivity in case the 1st terminal (4th terminal) and the 3rd terminal (6th terminal) are connected. The figure which shows the vehicle window glass mounting antenna apparatus in the 2nd Embodiment of this invention.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 shows a vehicle window glass-mounted antenna device 120 according to the first embodiment as a vehicle antenna device of the present invention, and FIG. 2 includes a vehicle window glass-mounted antenna device 120 in a rear window glass. A vehicle 100 is shown.

The vehicle antenna device of the present invention will be described as a receiving antenna for radio waves having a frequency of 76 to 108 MHz, for example.
A vehicle window glass-mounted antenna device 120 as a vehicle antenna device shown in FIG. 1 is mounted on the vehicle 100 of FIG. 2, and includes a rear window glass 108, a first antenna 101 and a second antenna on the rear window glass 108. 102, a first impedance matching circuit 103 and a second impedance matching circuit 104 corresponding to each antenna, a first receiving circuit 105 and a second receiving circuit 106 corresponding to each impedance matching circuit, and demodulation Part 107, first ground line 109 and second ground line 110 on rear window glass 108, first high-frequency switch 111 and second second switching part connected to each ground line And a second high-frequency switch 112 as a switching unit.

  The vehicle window glass-mounted antenna device 120 includes a first impedance matching circuit 103 and a second impedance matching circuit 104 for matching impedances corresponding to the first antenna 101 and the second antenna 102 to 50Ω. And a first receiving circuit 105 and a second receiving circuit 106 that select and amplify the received signal corresponding to each impedance matching circuit, and a demodulator 107 for demodulating the received signal into a data signal. Connected to receiving device.

  As will be described later, this receiving apparatus receives and demodulates radio waves by at least one of the antenna switching diversity method and the phase diversity method.

  However, “at least one of the antenna switching diversity method and the phase diversity method” includes that which operates by switching between the antenna switching diversity method and the phase diversity method in the receiving apparatus.

The first antenna 101 and the second antenna 102 are made of a conductive material, and are pasted on the rear window glass 108, for example, on the left and right sides (short sides).
The first antenna 101 includes the first feeding portion 113 of the first antenna 101 (portion connecting the antenna and the matching circuit) at the upper right end of the rear window glass 108 in the width direction, and the frame of the rear window glass 108 It arrange | positions substantially parallel along a side.

  The second antenna 102 is a lower end on the left side in the width direction of the rear window glass 108 and is opposed to the power feeding part of the first antenna. The second power feeding part 114 of the second antenna 102 (connects the antenna and the matching circuit). And a portion of the frame of the rear window glass 108 that is disposed substantially parallel to the side of the frame facing the first antenna 101.

  Therefore, the first antenna 101 and the second antenna 102 are arranged so that the first antenna 101 and the second antenna 102 are respectively located on the diagonal of the rear window glass 108.

  The line lengths of the first antenna 101 and the second antenna 102 are, for example, approximately ¼ wavelength of the FM radio operating frequency.

  The intervals between the first antenna 101 and the second antenna 102 and the side of the rear window glass 108 are arranged at a predetermined interval.

  Here, the predetermined interval is a length of about 1/50 wavelength, for example, in which the antenna gain does not decrease due to the proximity of the antenna and the vehicle metal ground.

  The first impedance matching circuit 103 and the second impedance matching circuit 104 match the antenna impedance to 50Ω, and are arranged on the vehicle 100 in the vicinity of the rear window glass 108.

  One of the first impedance matching circuit 103 and the second impedance matching circuit 104 is connected to the first antenna 101 and the second antenna 102, and the other is connected to the first receiving circuit 105 and the second receiving circuit. Connected to circuit 106.

  The first reception circuit 105 and the second reception circuit 106 include amplifiers that amplify the reception signals of the first antenna 101 and the second antenna 102, and are connected to the demodulation unit 107 that realizes diversity.

  The first ground wire 109 is made of a conductive material, and is arranged in the vicinity of the first antenna 101, for example, at an interval of about 1/50 wavelength, and has an angle of about 90 degrees with respect to the first antenna 101. In the L-shaped configuration with the open end formed on the side, the L-shaped horizontal portion is arranged substantially parallel to the upper side of the frame of the rear window glass 108, and the other end is connected to the first high-frequency switch 111. Is done.

  The second ground wire 110 is made of a conductive material, and is arranged in the vicinity of the second antenna 102, for example, at an interval of about 1/50 wavelength, and has an angle of about 90 degrees with respect to the second antenna 102. In the L-shaped configuration with the open end formed on the side, the L-shaped horizontal portion is arranged substantially parallel to the lower side of the frame of the rear window glass 108, and the other end is connected to the second high-frequency switch 112. Is done.

  The line lengths of the first ground line 109 and the second ground line 110 are, for example, approximately ¼ wavelength of the FM radio operating frequency.

  The first high-frequency switch 111 includes three terminals (for example, a first terminal 111a, a second terminal 111b, and a third terminal 111c). The first terminal 111a is connected to the first ground wire 109, and the second terminal 111b is not connected, and the third terminal 111c is grounded to the vehicle 100 ground.

  Further, the second high-frequency switch 112 includes three terminals (for example, a fourth terminal 112a, a fifth terminal 112b, and a sixth terminal 112c), and the fourth terminal 112a is connected to the second ground wire 110, The fifth terminal 112b is not connected, and the sixth terminal 112c is grounded to the vehicle 100 ground.

  Therefore, the first high-frequency switch 111 (second high-frequency switch 112) is connected to the first terminal 111a (fourth terminal 112a) and the second terminal 111b (fifth terminal 112b), or the first terminal 111a. It switches so that (4th terminal 112a) and 3rd terminal 111c (6th terminal 112c) may be connected.

  When the first terminal 111a (fourth terminal 112a) and the second terminal 111b (fifth terminal 112b) of the first high-frequency switch 111 (second high-frequency switch 112) are connected, the first terminal Ground line 109 and second ground line 110 are open (not connected) to vehicle 100 ground in terms of high frequency, and do not operate as ground lines.

  On the other hand, when the first terminal 111a (fourth terminal 112a) and the third terminal 111c (sixth terminal 112c) of the first high-frequency switch 111 (second high-frequency switch 112) are connected, the first terminal Ground line 109 (second ground line 110) is short-circuited (connected) to vehicle 100 ground at a high frequency and operates as a ground line.

  Next, the operation of the vehicle antenna device according to the first embodiment of the present invention will be described using the directivity pattern of FIG.

  Here, when the first terminal 111a (fourth terminal 112a) and the second terminal 111b (fifth terminal 112b) of the first high-frequency switch 111 and the second high-frequency switch 112 are connected, the first ground wire Since 109 and the second ground wire 110 are open at high frequencies, the directivity of each of the first antenna 101 and the second antenna 102 can be obtained.

  The directivity of each antenna on the horizontal plane (XY plane) in this case is shown in FIG. As shown in FIG. 3A, the maximum directivity direction of the first antenna 101 is the X direction, and the maximum directivity direction of the second antenna 102 is the −X direction. That is, the directivity is different from each other, and directivity suitable for the antenna switching diversity method is obtained.

  On the other hand, when the first terminal 111a (fourth terminal 112a) and the third terminal 111c (sixth terminal 112c) of the first high-frequency switch 111 and the second high-frequency switch 112 are connected, the first ground wire 109 is connected. The second ground wire 110 is short-circuited to the vehicle 100 ground in a high frequency manner.

  In this case, since the antenna currents of the first antenna 101 and the second antenna 102 are distributed on the first ground line 109 and the second ground line 110, the current distribution of each antenna changes to change the antenna current. The directivity of each other changes, and the same directivity is obtained.

  The directivity of each antenna on the horizontal plane (XY plane) in this case is shown in FIG. From FIG. 3B, the maximum directivity direction of the first antenna 101 is the X to Y direction and the −X to −Y direction, and the maximum directivity direction of the second antenna 101 is the X to Y direction and −X. The directivity suitable for the phase diversity method is obtained because of the same directivity as the -Y direction.

  Therefore, by using the first high-frequency switch 111 and the second high-frequency switch 112 that can manually switch the switch, the directivity suitable for different diversity systems with the same antenna configuration can be obtained in the manufacturing stage. Since this can be realized by switching the first high-frequency switch 111 and the second high-frequency switch 112 of the first ground line 109 and the second ground line 110, the manufacturing cost can be reduced.

  According to the present embodiment, the first ground wire 109 and the second ground wire 110 are placed close to the first antenna 101 and the second antenna 102 on the rear window glass 108, and the first ground wire is disposed. By adopting an antenna configuration in which the first high-frequency switch 111 and the second high-frequency switch 112 are used to switch the short-circuit point between the 109 and the second ground line 110 and the vehicle 100 ground, the directivity corresponding to different diversity systems with the same antenna configuration Therefore, high reception performance can be secured with a simple configuration, and the manufacturing cost can be reduced.

  In the present embodiment, the first antenna 101 and the second antenna 102, the first ground wire 109, and the second ground wire 110 are arranged on the rear window glass 108. The same effect can be obtained even if it is placed on the window glass.

  In the present embodiment, the first antenna 101 and the second antenna 102 are disposed along the left and right sides of the rear window glass 108, and the first ground line 109 and the second ground line 110 are disposed on the rear window glass. 108, the first antenna 101 and the second antenna 102 are arranged along the upper and lower sides, and the first ground line 109 and the second ground line are arranged. The same effect can be obtained by arranging 110 along the left and right sides of the rear window glass 108.

  Furthermore, although the present embodiment has been described as an antenna for FM reception, a similar effect can be obtained even with an antenna for digital television reception.

(Second Embodiment)
Next, a second embodiment of the present invention will be described in detail with reference to FIG. In the present embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals to avoid redundant description.

  The vehicle window glass-mounted antenna device 220 in FIG. 4 is different from the vehicle window glass-mounted antenna device 120 in FIG. 1 in that the demodulator 207, the first high-frequency switch 211, and the second high-frequency switch 212 are connected by a control line. The first high frequency switch 211 and the second high frequency switch 212 are switched by the control signal 213 and the control signal 214 output from the demodulator 207.

  Here, the operation when the vehicle window glass-mounted antenna device 220 according to the second embodiment of the present invention is mounted on the rear window glass will be described.

  For example, when the antenna switching diversity method is selected as the initial setting, the demodulation unit 207 uses the control signal 213 and the control signal 214 from the demodulation unit 207 to switch the first high frequency switch 211 (second high frequency switch 212). The first terminal 211a (fourth terminal 212a) and the second terminal 211b (fifth terminal 212b) are set to be connected.

  By setting so that the first terminal 211a (fourth terminal 212a) and the second terminal 211b (fifth terminal 212b) of the first high-frequency switch 211 (second high-frequency switch 212) are connected, Since the first ground line 109 and the second ground line 110 are open in terms of high frequency, they have different directivities as shown in FIG. 3A, and FM broadcasting with directivity suitable for the antenna switching diversity method. Receive a signal.

  Here, when the signal level received by the first antenna 101 or the second antenna 102 is equal to or lower than the level that can be demodulated by the demodulator 207, the demodulator 207 changes the diversity system from the antenna switching diversity system to the phase diversity system. The high frequency switch 211 and the third terminal 211c (sixth terminal 212c) and the third terminal 211c (sixth terminal 212c) of the high frequency switch 211 (second high frequency switch 212) are connected from the switching and demodulating unit 207. The control signal 213 and the control signal 214 are output to the second high frequency switch 212.

  The control signal 213 and the control signal 214 are switched so that the first terminal 211a (fourth terminal 212a) and the third terminal 211c (sixth terminal 212c) of the high-frequency switch 211 (second high-frequency switch 212) are connected. As a result, the first ground line 109 and the second ground line 110 are short-circuited to the ground of the vehicle 100 and have the same directivity as shown in FIG. 3B, and the directivity suitable for the phase diversity method. The FM broadcast signal is received at.

  That is, by selecting a diversity method according to the propagation environment and switching to a directivity according to the diversity method, the diversity performance can be improved and high sensitivity performance can be obtained.

  Therefore, according to the present embodiment, the first ground wire 109 and the second ground wire 110 are placed close to the first antenna 101 and the second antenna 102 on the rear window glass 108, and the demodulator 207. The diversity method is selected in accordance with the reception performance, and the short-circuit point between the first ground wire 109 and the second ground wire 110 and the vehicle 100 ground is set to the first high-frequency switch 211 and By adopting the antenna configuration switched by the second high-frequency switch 212, the directivity corresponding to different diversity systems can be realized with the same antenna configuration according to the propagation environment, so that the diversity performance can be improved with a simple configuration and high. Reception performance can be secured.

As described above, according to the present invention, the first antenna disposed along one side of the glass frame on the rear window glass, and the glass on the rear window glass facing the first antenna. A second antenna disposed along the other side of the frame; a first reception circuit and a second reception circuit connected to the first antenna and the second antenna; and a first reception. A demodulator connected to the circuit and the second receiving circuit, and a first ground line and a second ground on the rear window glass disposed substantially perpendicular to the first antenna and the second antenna. And a short-circuit point of the first ground line and the second ground line (short-circuit point with the ground), and the high-frequency short-circuit point of the heater conductor is increased in accordance with the diversity system of the demodulator Depending on the configuration to switch between connected and disconnected, each die To the antenna configuration according to the Shichi scheme can be realized by the same configuration, it is possible to provide a vehicle antenna device according to inexpensive mass production costs.

  Further, the diversity system selection means and the short-circuit point switching means corresponding thereto may be configured to use a reception performance comparison result of the demodulation unit. With this configuration, a high reception sensitivity performance can be ensured by selecting a diversity method according to the propagation environment and switching to an antenna directivity suitable for it.

  The vehicle antenna device of the present invention has the effect of realizing directivity control according to the diversity method with the same antenna configuration and exhibiting high sensitivity performance. For example, an antenna mounted on a vehicle rear window glass Useful for devices.

DESCRIPTION OF SYMBOLS 100 Vehicle 101 1st antenna 102 2nd antenna 103 1st impedance matching circuit 104 2nd impedance matching circuit 105 1st receiving circuit 106 2nd receiving circuit 107,207 Demodulator 108 Rear window glass 109 1st 110 ground wire 110 second ground wire 111, 112 high frequency switch 111a first terminal 111b second terminal 111c third terminal 112a fourth terminal 112b fifth terminal 112c sixth terminal 113 first power feeding portion 114 second power feeding portion 120, 220 Vehicle window glass mounted antenna device 211, 212 High frequency switch 211a First terminal 211b Second terminal 211c Third terminal 212a Fourth terminal 212b Fifth terminal 212c Sixth terminal 213, 214 Control signal

Claims (3)

In a vehicle antenna device that is mounted on a vehicle and connected to a receiving device that demodulates radio waves in at least one of an antenna switching diversity method and a phase diversity method,
A first antenna provided on the window glass of the vehicle, provided at a predetermined interval from the window glass along one short side of the window glass, and the first antenna on the window glass The second antenna provided at a predetermined interval from the window glass along the other short side opposite to the window, the power supply unit of the first antenna, and the power supply unit of the second antenna are the windows. Provided respectively on the diagonals of the glass, close to the feeding portion of the first antenna, and along one long side of the window glass at an angle of 90 degrees with respect to the first antenna The first ground wire and the second antenna are provided close to the feeding portion and along the other long side of the window glass at an angle of 90 degrees with respect to the second antenna. A second ground line and the first ground connected to the first ground line The first switching unit that switches the connection between the ground and the ground to connection or disconnection at a high frequency, and the connection between the second ground and the ground that is connected to the second ground line is connected or disconnected at a high frequency A vehicle antenna device comprising: a second switching unit that switches to The first switching unit includes a first terminal connected to the first ground line, a second terminal that is open at a high frequency, and a third terminal that is grounded to the ground. The switching unit has a fourth terminal connected to the second ground wire, a fifth terminal that is open at high frequency, and a sixth terminal that is grounded to the ground,
The first terminal and the second terminal are connected and the fourth terminal and the fifth terminal are connected, or the first terminal and the third terminal are connected and the fourth terminal and the second terminal are connected. The vehicular antenna according to claim 1, wherein the connection between the first ground line and the second ground line and the ground is switched to connection or disconnection in terms of high frequency by being connected to six terminals. apparatus. The receiving device switches the antenna switching diversity method and the phase diversity method according to the reception status of the input radio wave, demodulates the radio wave, and outputs a control signal according to the reception status input to the receiving device Because
The first switching unit and the second switching unit connect the first ground line and the connection between the second ground line and the ground in high frequency according to a control signal output from the receiving device. 3. The vehicle antenna device according to claim 2, wherein the vehicle antenna device is switched to non-connection.