JP2009200684A - Antenna apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antenna apparatus in which a structure is simple, and a HPBW (Half Power Beam Width) is wide. <P>SOLUTION: The antenna apparatus 1 of a rear spoiler built-in type is provided with: a dipole antenna 3 formed by a front surface side conductive layer of a printed circuit board 2; and a matching circuit 12 formed by a rear surface side conductive layer of the printed circuit board 2. The dipole antenna 3 includes: dipole elements 4, 5 arranged in a trapezoid shape; and auxiliary elements 6, 7 connected to back sides of top units of the respective dipole elements 4, 5. The antenna apparatus 1 is thereby provided in which the structure is simple and the HPBW is wide. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an antenna device, and more particularly to an antenna device formed using a printed circuit board.

Conventionally, an automobile is provided with an antenna device for receiving a television broadcast or the like. Further, by providing the antenna device in the rear spoiler, the space is effectively used and the appearance of the automobile is improved (for example, see Patent Document 1).
JP 2003-309212 A

  However, the rear spoiler built-in antenna device for in-vehicle digital terrestrial television has a simple structure and no HPBW (Half Power Beam Width).

  Therefore, a main object of the present invention is to provide an antenna device having a simple structure and a wide HPBW.

  An antenna device according to the present invention is an antenna device formed using a printed circuit board, and includes a dipole antenna formed of a front surface side conductive layer of the printed circuit board and a matching circuit formed of a back surface side conductive layer of the printed circuit board. It is equipped with. The dipole antenna includes first and second dipole elements and first and second auxiliary elements. The first and second dipole elements are arranged in a square shape with their proximal ends approaching and their distal ends spaced apart. One end of each of the first and second auxiliary elements is connected to a portion of the tip portion of each of the first and second dipole elements that is opposite to the boresight direction of the dipole antenna. Therefore, since the dipole antenna and the matching circuit are provided on the front and back of the printed circuit board, the structure can be simplified. In addition, since the first and second diode elements are arranged in a square shape and the first and second auxiliary elements are provided at the tips of the first and second diode elements, a wide HPBW can be obtained. it can.

  Preferably, the matching circuit includes a gamma-type matching line that couples the coaxial line and the first and second dipole elements. The gamma-type matching line includes an output terminal connected to the internal conductive line of the coaxial line, and first and second power supply terminals provided to face the base ends of the first and second dipole elements, respectively. A first line connected between the output terminal and the first power supply terminal, and a second line connected in parallel to at least a part of the first line and having one end connected to the second power supply terminal. And a third line connected between the first and second power supply terminals. The matching circuit is further arranged in parallel with the first stub, one end connected to the other end of the second line, the other end provided opposite to the first line, And a second stub having one end connected to the first line. In this case, since the first and second stubs are provided, VSWR (Voltage Standing Wave Ratio) can be lowered.

  Preferably, the base end portions of the first and second dipole elements are arranged along one long side of the rectangular antenna region, and the tip end portion of the first dipole element is one short side and the other side of the antenna region. The second dipole element is disposed at a corner where the side long sides intersect, and the tip of the second dipole element is disposed at a corner where the other short side of the antenna region intersects with the one long side. The first auxiliary element is disposed along the other long side of the antenna region, the second auxiliary element is disposed along the other short side of the antenna region, and the first auxiliary element is the second auxiliary element. Longer than the element. In this case, the boresight direction can be directed obliquely and the depth of the antenna device can be shortened.

  Preferably, the antenna device is built in an end portion of the rear spoiler of the automobile, and the antenna region is arranged substantially horizontally with an angle at which the one side long side and the one side short side intersect with each other at the corner of the rear end of the automobile. This antenna device is suitable as a rear spoiler built-in antenna device.

  As described above, with the antenna device according to the present invention, a wide HPBW can be obtained with a simple structure. In addition, VSWR can be lowered. Further, the boresight direction can be directed obliquely and the depth of the antenna device can be shortened. This antenna device is suitable as a rear spoiler built-in antenna device.

  FIG. 1 is a view of a rear spoiler built-in antenna device 1 according to an embodiment of the present invention as viewed from the front side. The antenna device 1 is built in a rear spoiler of an automobile, receives radio waves of terrestrial digital television broadcasting, and supplies the received radio waves (high-frequency signals) to an in-vehicle terrestrial digital television via a coaxial line.

  In FIG. 1, the antenna device 1 includes a printed circuit board 2 and a dipole antenna 3 formed of a surface side conductive layer of the printed circuit board 2. As the printed board 2, a double-sided printed board having a thickness of 1.6 mm was used. The dipole antenna 3 includes two dipole elements 4 and 5 and two auxiliary elements 6 and 7. Each of the dipole elements 4 and 5 is basically formed in a fan shape (fan shape) that gradually becomes wider from the base end toward the tip end. Thus, by making each of the dipole elements 4 and 5 into a fan shape, the frequency band of the antenna device 1 can be widened. The length of each of the dipole elements 4 and 5 is set to about a quarter of the wavelength of the radio wave of digital terrestrial television broadcasting.

  Each of the auxiliary elements 6 and 7 is formed in an elongated strip shape. The two dipole elements 4 and 5 are arranged in a square shape with their proximal end portions close to each other and their distal end portions separated from each other. One end of each of the auxiliary elements 6 and 7 is connected to a portion on the opposite side to the bore sight direction of the dipole antenna 3 in the tip portion of each of the dipole elements 4 and 5.

  That is, assuming a rectangular antenna region 8 of 202 mm × 83 mm in a plane including the surface of the printed circuit board 2, the base end portions of the dipole elements 4 and 5 are arranged along the one side long side 8 a of the antenna region 8, The tip of the dipole element 4 is arranged at the corner where the one short side 8b and the other long side 8c of the antenna region 8 intersect, and the tip of the dipole element 5 is the other short side 8d of the antenna region 8 and the one long side. It is arranged at the corner where 8a intersects.

  The auxiliary element 6 is disposed along the other long side 8 c of the antenna region 8, and one end thereof is connected to the tip end portion of the dipole element 4. The auxiliary element 7 is disposed along the other short side 8 d of the antenna region 8, and one end thereof is connected to the tip of the dipole element 5. The length (38 mm) of the auxiliary element 6 is set longer than the length (27 mm) of the auxiliary element 7.

  In this way, the dipole elements 4 and 5 are arranged in a C-shape, and the auxiliary elements 6 and 7 are provided on the rear side (opposite to the boresight direction) of the dipole elements 4 and 5, so that the HPBW is Wide angle can be achieved.

  Further, the dipole element 4 is disposed obliquely with respect to the front direction (right direction in FIG. 1) of the antenna device 1, and the auxiliary element 6 on the dipole element 4 side is more than the auxiliary element 7 on the dipole element 5 side. The boresight direction can be directed obliquely by slightly increasing the length. If the antenna device 1 is installed at the corner of the automobile, the reflectance of the reflector formed by the body of the automobile is also unbalanced between the left and right sides of the antenna device 1, so that the inclination in the boresight direction is further increased.

  In addition, since the dipole antenna 3 is disposed in the rectangular antenna region 8, the depth of the antenna device 1 can be shortened as compared with the case where it is disposed in the square antenna region.

  The antenna device 1 also includes a ground terminal 9 and ground wires 10 and 11 formed of a surface-side conductive layer of the printed circuit board 2. The ground terminal 9 is provided outside the antenna region 8 along the end of the antenna region 8 on the other side short side 8d side of the other side long side 8c. The ground terminal 9 is connected to a coaxial external conductive line that connects the antenna device 1 and the in-vehicle digital terrestrial television. The external conductive line of the coaxial line is connected to the main body (earth) of the automobile on the TV side. The ground wires 10 and 11 are formed in a wide band shape and are arranged in parallel to each other, and are connected between the base ends of the dipole elements 4 and 5 and the ground terminal 9, respectively.

  FIG. 2 is a diagram of the configuration of the antenna device 1 as viewed from the front surface side. From the antenna device 1 shown in FIG. 1, the conductive layer (dipole antenna 3, ground terminal 9, and ground wire 10) 11) and the insulating substrate are removed. In FIG. 2, the antenna device 1 further includes a matching circuit 12 formed of a back surface side conductive layer of the printed circuit board 2. Thus, by forming the dipole antenna 3 and the matching circuit 12 with the conductive layers on the front and back sides of the printed circuit board 2, the antenna device 1 having a thin and simple structure can be realized. In addition, since parts such as a balun are not used, the cost can be reduced accordingly.

  The matching circuit 12 includes a gamma-type matching line 13 that couples the coaxial line and the dipole elements 4 and 5. The gamma matching line 13 includes an output terminal 14, two power supply terminals 15 and 16, and lines (microstrip lines) 17 to 19. The output terminal 14 is provided to face the central portion of the ground terminal 9 across the insulating substrate of the printed circuit board 2, and is connected to the internal conductive line of the coaxial line. The power supply terminals 15 and 16 are provided to face the base ends of the dipole elements 4 and 5, respectively, with the insulating substrate of the printed board 2 interposed therebetween.

  The line 17 is connected between the output terminal 14 and the power supply terminal 15. The length of the line 17 is set to a length of about one quarter of the wavelength of the radio wave of digital terrestrial television broadcasting. The line 18 is connected between the power supply terminals 15 and 16. The line 19 is arranged in parallel to a part of the line 17, and one end thereof is connected to the power supply terminal 16. The line width of each of the lines 17 to 19 is set to 2 mm. The distance between the lines 17 and 19 is set to 23.5 mm.

  The matching circuit 12 includes three stubs 20-22. One end of the stub 20 is connected to the other end of the line 19, and the other end is provided to face the line 17. The stub 20 is provided at a right angle to the line 19. The stub 21 is arranged in parallel with the stub 20, and one end thereof is connected to the line 17. The line width of the stubs 20 and 21 is set to 1.5 mm, and the distance between the stubs 20 and 21 is set to 2 mm. The stub 22 is connected to the line 17 in the vicinity of the output terminal 14. In particular, the VSWR can be lowered by providing the stubs 20 and 21.

  FIG. 3 is a view of an automobile on which the antenna device 1 is mounted as viewed obliquely from the rear. In FIG. 3, the rear spoiler 23 is provided at the upper end of the rear end of the body 24 of the automobile. The rear spoiler 23 is formed of a resin and has a hollow structure as shown in FIGS. 4A is a sectional view taken along line IVA-IVA in FIG. 4B, and FIG. 4B is a sectional view taken along line IVB-IVB in FIG.

  The antenna device 1 is built substantially horizontally at the right end when viewed from the rear of the rear spoiler 23 of the automobile. In the antenna device 1, the short sides 8b and 8d of the antenna region 8 coincide with the front-rear direction (traveling direction) of the automobile, and the angle at which the one side long side 8a and the one side short side 8b intersect is viewed from the rear of the automobile. Arranged to be located at the right corner. The boresight direction of the antenna device 1 is directed to a 45 degree direction diagonally right behind the automobile.

  Further, another antenna device 25 is built in the left end portion when viewed from the rear of the rear spoiler 23 of the automobile. The antenna device 25 is formed symmetrically with the antenna device 1 with the short side 8d of the antenna region 8 of FIG. Also in the rear spoiler 23, the antenna devices 1 and 25 are symmetrically arranged on both sides of the center line in the longitudinal direction of the automobile. The bore sight direction of the antenna device 1 is directed to a 45 degree direction diagonally to the left of the automobile.

  FIG. 5 is a block diagram showing a configuration of a terrestrial digital television receiving system of an automobile. In FIG. 5, the terrestrial digital television reception system includes four antenna devices 1, 25 to 27, amplifiers 28 to 31, a switching circuit 32, and a terrestrial digital television 33. The antenna devices 1 and 25 are as described in FIGS. 1 to 3 and FIGS. 4 (a) and 4 (b).

  The antenna device 26 includes a film-like antenna provided at the left end of the windshield of the automobile and a matching circuit. The antenna device 27 includes a film-like antenna provided at the right end of the windshield of the automobile and a matching circuit. The antenna devices 26 and 27 receive radio waves transmitted from a direction of 180 degrees in front of the automobile. The antenna devices 1 and 25 receive radio waves transmitted from a direction of 180 degrees behind the automobile. Therefore, the HPBW of each of the antenna devices 1 and 25 is set to be approximately 90 degrees, the bore sight direction of the antenna apparatus 1 is set to a 45 ° diagonal direction, and the bore sight direction of the antenna device 25 is a 45 ° diagonal left direction. Set to direction. Therefore, any one of the antenna devices 1, 25 to 27 can receive radio waves transmitted from the direction of 360 degrees of the automobile.

  The amplifiers 28 to 31 amplify the output signals of the antenna devices 1 to 25 to 27, respectively. The switching circuit 32 is controlled by the tuner of the terrestrial digital television 33, and connects the antenna device having the highest output signal level among the antenna devices 1, 25 to 27 to the terrestrial digital television 33. The terrestrial digital television 33 displays the video of the program selected by the viewer based on the signal received by the antenna device selected by the switching circuit 32.

  FIG. 6 is a diagram illustrating the frequency characteristics of the gain in the boresight direction of the antenna device 25. In Japan, the frequency range of broadcast radio waves in terrestrial digital broadcasting is 470 to 710 MHz. From FIG. 6, it can be seen that the antenna device 25 has a sufficiently high gain at 470 to 710 MHz.

  The measurement of the gain is performed by using a grounded metal plate having a width of 500 mm and a height of 150 mm instead of the body 24 of the automobile and horizontally arranging the antenna device 25 at the center of the left corner of the metal plate. It was. Further, in a normal antenna device for UHF television broadcasting, the distance between the antenna device and the reflector is set to about 15 cm. However, since this antenna device 25 needs to be provided in the narrow rear spoiler 23, the antenna device 25 is provided. And the distance between the metal plate (reflector) was set to 4 cm. The following measurements were also performed under the same conditions.

  FIG. 7 is a diagram illustrating the frequency characteristics of the VSWR of the antenna device 25. It can be seen from FIG. 7 that this antenna device 25 has a sufficiently low VSWR at 470 to 710 MHz.

  8A to 8F are diagrams illustrating the frequency characteristics of the horizontal plane directivity of the antenna device 25. FIG. 8A to 8F, the 0 degree direction corresponds to the front direction of the antenna device 25 (rear of the automobile). From this characteristic, it can be seen that the antenna device 25 has a unidirectionality of 45 degrees and a wide HPBW.

  FIGS. 9A to 9F are diagrams showing the frequency characteristics of the directivity of the vertical plane of the antenna device 1. 9A to 9F, the 0 degree direction corresponds to the front direction of the antenna device 25 (rear of the automobile), and the 270 degree direction corresponds to the upper side of the antenna apparatus 25 (above the automobile). From this characteristic, it can be seen that the antenna device 25 has a single directivity in an obliquely upward direction and a wide HPBW.

  FIGS. 10A to 10F are diagrams showing the effects of the auxiliary elements 6 and 7 shown in FIG. FIGS. 10A to 10C are diagrams illustrating the frequency characteristics of the horizontal plane directivity of the antenna device 25 when the auxiliary elements 6 and 7 are present. FIGS. 10D to 10F are diagrams illustrating the auxiliary element 6. , 7 is a diagram illustrating the frequency characteristics of the horizontal plane directivity of the antenna device 25 in the absence of. 10A to 10F, when the auxiliary elements 6 and 7 are not provided, the directivity of the antenna device 25 is substantially directed to the front, but by providing the auxiliary elements 6 and 7, the directivity may be oblique to the right. I understand.

  FIG. 11 is a diagram illustrating the effect of the stubs 20 and 21 shown in FIG. 1, and the VSWR frequency characteristics of the antenna device 25 when the stubs 20 and 21 are present and the antenna device when the stubs 20 and 21 are not present. It is a figure which compares the frequency characteristic of 25 VSWR. It can be seen from FIG. 11 that the VSWR can be lowered by providing the stubs 20 and 21.

  In this embodiment, the case where the present invention is applied to the rear spoiler built-in antenna devices 1 and 25 has been described. However, the present invention is not limited to this, and the present invention can be applied to a general UHF television broadcast antenna device. Needless to say.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a figure which shows the structure of the dipole antenna contained in the antenna apparatus with a built-in rear spoiler by one Embodiment of this invention. It is a figure which shows the structure of the matching circuit contained in the antenna apparatus shown in FIG. It is a figure which shows the motor vehicle carrying the antenna apparatus shown in FIG. It is sectional drawing which shows the rear spoiler shown in FIG. 3, and the antenna device incorporated in it. It is a block diagram which shows the structure of the terrestrial digital television broadcast receiving system mounted in the motor vehicle shown in FIG. It is a figure which shows the frequency characteristic of the gain of the antenna apparatus shown in FIG. It is a figure which shows the frequency characteristic of VSWR of the antenna apparatus shown in FIG. It is a figure which shows the frequency characteristic of the horizontal surface directivity of the antenna apparatus shown in FIG. It is a figure which shows the frequency characteristic of the vertical surface directivity of the antenna apparatus shown in FIG. It is a figure which shows the effect of the auxiliary element shown in FIG. It is a figure which shows the effect of the stub shown in FIG.

Explanation of symbols

  1,25-27 antenna device, 2 printed circuit board, 3 dipole antenna, 4,5 dipole element, 6,7 auxiliary element, 8 antenna area, 9 earth terminal, 10,11 earth wire, 12 matching circuit, 13 gamma type matching Lines, 14 output terminals, 15, 16 power supply terminals, 17-19 lines, 20-22 stubs, 23 rear spoilers, 24 bodies, 28-31 amplifiers, 32 switching circuits, 33 terrestrial digital television.

Claims (4)

An antenna device formed using a printed circuit board,
A dipole antenna formed of a surface-side conductive layer of the printed circuit board;
A matching circuit formed of a back side conductive layer of the printed circuit board,
The dipole antenna includes first and second dipole elements and first and second auxiliary elements,
The first and second dipole elements are arranged in a C-shape with their proximal ends close to each other and their distal ends separated from each other,
One end of each of the first and second auxiliary elements is connected to a portion opposite to the bore sight direction of the dipole antenna at the tip of the first and second dipole elements, respectively. An antenna device. The matching circuit includes a gamma-type matching line that couples a coaxial line and the first and second dipole elements,
The gamma-type matching line is
An output terminal connected to the inner conductive line of the coaxial line;
First and second power supply terminals provided to face the base ends of the first and second dipole elements, respectively;
A first line connected between the output terminal and the first power supply terminal;
A second line provided in parallel with at least a part of the first line and having one end connected to the second power supply terminal;
A third line connected between the first and second power supply terminals,
The matching circuit is
Furthermore, a first stub having one end connected to the other end of the second line and the other end facing the first line;
The antenna device according to claim 1, further comprising: a second stub arranged in parallel with the first stub and having one end connected to the first line. The base ends of the first and second dipole elements are disposed along one long side of the rectangular antenna region,
The tip portion of the first dipole element is disposed at a corner where one short side and the other long side of the antenna region intersect,
The tip of the second dipole element is disposed at an angle where the other side short side of the antenna region and the one side long side intersect,
The first auxiliary element is disposed along the other long side of the antenna region,
The second auxiliary element is disposed along the other short side of the antenna region,
The antenna device according to claim 1, wherein the first auxiliary element is longer than the second auxiliary element. The antenna device is built in an end part of a rear spoiler of an automobile,
The antenna device according to claim 3, wherein the antenna region is disposed substantially horizontally with an angle at which the one long side intersects with the one short side being a corner of the rear end of the automobile. .

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