JP5749890B2 - Vehicle antenna - Google Patents

Description

  The present invention relates to a vehicle antenna, and more particularly to a vehicle antenna that functions as a monopole antenna with an expanded element width.

  Conventionally, vehicles are equipped with a plurality of antennas such as radios and televisions. Radio waves received by the vehicle include AM radio medium wave (MW), FM radio and analog television ultra-high frequency (VHF), analog television and digital television ultra-high frequency (UHF), and the like. In addition, such an antenna is disposed in an exterior product constituting a resin hollow body such as a vehicle air spoiler or a vehicle bumper when mounted on a glass (front, rear, side) of a vehicle. Some of them have improved the overall appearance of the vehicle and shared the space.

  For example, Patent Document 1 discloses a sheet antenna that is used by being attached to transparent glass, and in which the antenna element is difficult to visually recognize and does not impair the visibility and appearance of the transparent glass. In this sheet antenna, an antenna element is formed on a film by forming an assembly of thin linear conductors by etching a conductive foil or by wire. However, since the antenna depends on the shape, the shape is determined, and it is difficult to make an antenna with a new design. The seat antenna of Patent Document 1 is also a loop antenna, and is conscious of the design shape. It wasn't.

  FIG. 7 shows an example of a vehicle antenna 30 using a conventional monopole antenna, and a front view and a top view of the vehicle antenna 30 are shown. The vehicular antenna 30 includes a wide element 11 formed on the PET film 18 using silver paste ink, which is a conductive ink, a pattern of GNDs 15 and 16 formed in the same manner using silver paste ink, and a feeding point 14. , And another sheet of PET film 17 is stacked on the element 11 and vacuum pressed. In this way, it can be formed as an antenna for digital television.

  In general, it is known that a wide band can be achieved by increasing the element width of a monopole antenna. Non-Patent Document 1 discloses that by increasing the element width of a monopole antenna, the input impedance does not change even if the antenna length is slightly changed, and the characteristics change even if the wavelength of the electric wave to be fed is changed. There is a description that it can be reduced and can have a broadband characteristic.

JP 2007-13770 A

Tonobu Tanaka, “Wire Antenna”, CQ Publishing Co., Ltd., March 1, 1993, P27-28

  However, we are aware of the design shape, reduce the element area so as not to impede visual recognition without degrading the antenna performance, and improve the productivity and further reduce the cost of the vehicle antenna. It was difficult to make.

  Therefore, the vehicle antenna according to the present invention is provided with a notch or a mesh-shaped several-millimeter punch hole in order to reduce the element area while being aware of the design shape, without reducing the antenna performance. An object of the present invention is to provide a vehicle antenna with a reduced element area.

Above, in order to achieve the object, a vehicle antenna according to the present invention includes a rectangular type conductor which forms a monopole antenna, and a feed point which is connected to one end of the rectangular type conductor, said rectangular type conductor includes a notch from the short side of the other end side cutaway conductors in the longitudinal direction, than the notch provided on the feed point side, and a mesh portion having a plurality of cutouts holes, The mesh portion and the cutout portion are formed on the same surface . The vehicle antenna according to the present invention is desirably provided in exterior parts of the vehicle, the rectangular type conductor is printed on a plastic film. Further, the present invention provides an antenna for a vehicle, comprising: a rectangular type conductor which forms a monopole antenna, and a feed point which is connected to one end of the rectangular type conductor, the rectangular type conductor, the other from the short sides of the end side and notch portion formed by cutting a conductor in the longitudinal direction, than the notch provided on the feed point side has a mesh portion having a plurality of cutouts holes, a conductive foil The mesh part and the notch part are formed on the same plane .

The vehicle antenna according to the present invention, desirably, the cutout holes of mesh portion has a polygonal shape which have a length of a predetermined side, provided on the other end side of the rectangular type conductor switching Operation-away portion that is has a predetermined length in the short side direction of the other end, a length extending from the other end in the long side direction, and each in a range that does not bandwidth deterioration of antenna characteristics Set the length.

  According to the vehicle antenna according to the present invention, the area of the conductive foil and the amount of conductive ink used can be reduced without reducing the performance of the antenna characteristics by providing the rectangular conductor with a notch or a mesh-shaped hole. It is possible to realize a vehicular antenna.

It is a block diagram explaining the structure of the vehicle antenna which concerns on embodiment of this invention. It is the enlarged view to which the mesh part in the vehicle antenna of FIG. 1 was expanded. It is a reference lineblock diagram of a vehicular antenna used as a reference in understanding an embodiment of the present invention. FIG. 4 is a characteristic diagram showing a characteristic of a bandwidth ratio with respect to an area ratio in the vehicle antenna of FIG. 3. It is a reference lineblock diagram of a vehicular antenna used as a reference in understanding an embodiment of the present invention. FIG. 6 is a characteristic diagram illustrating a characteristic of a bandwidth reduction ratio according to an X direction dimension and a Y direction dimension in the vehicle antenna of FIG. 5. It is a block diagram which shows an example of the vehicle antenna by the conventional monopole antenna. FIG. 2 is a characteristic diagram showing a characteristic of a bandwidth ratio with respect to an area ratio in the vehicle antenna of FIG. 1. It is explanatory drawing explaining the mounting position of the vehicle antenna which concerns on embodiment of this invention. It is a lower half casing of the air spoiler which mounts the antenna for vehicles concerning the embodiment of the present invention. It is the enlarged view to which the vehicle antenna of FIG. 10 was expanded.

  Hereinafter, the best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described with reference to the drawings.

  FIG. 1 shows a configuration of a vehicle antenna 10 according to the present invention. The vehicular antenna 10 is a digital television antenna for terrestrial digital broadcasting. The vehicular antenna 10 includes an element 11 formed on the PET film 18 using conductive ink, a pattern of GNDs 15 and 16, and an element 11. And a feeding point 14 for connecting GND 15 and GND 16, and another PET film 17 is stacked on the element 11 and vacuum pressed. The element 11 includes a cutout portion 12 in which the element 11 is cut out in a rectangular shape from one end, and a mesh portion 13 formed by a plurality of rectangular shapes having a predetermined pitch and opening size. In FIG. 1, for the sake of explanation, the rectangular shape in the mesh portion 13 is enlarged and displayed, but the pitch and the opening size have a fine shape of about several millimeters.

  FIG. 2 shows an enlarged view of the mesh portion 13 in the vehicle antenna of FIG. 1, and FIG. 2 (A) shows a standard quadrangular mesh portion 13. The mesh part 13 is formed by, for example, leaving conductive ink in an area having a pitch of 3 mm or more and an opening size of 2 mm or more. 2B shows a triangle as another rectangular shape in FIG. 2A, and FIG. 2C shows a hexagon. 2A to 2C may be used separately. For example, with the rectangular shape of FIG. 2A as the background, the triangle of FIG. 2B or the six of FIG. You may use a square as a dot which forms a character or a mark. By using such a method, it is possible to display an arbitrary mark or character on the mesh portion, and it is possible to reduce the conductive ink to be used and increase the degree of freedom of the design.

  Next, the mounting position of the vehicle antenna in FIG. 1 will be described with reference to FIGS. FIG. 9 shows the mounting position of the vehicle antenna according to the embodiment of the present invention, and FIG. 10 shows the lower half casing of the air spoiler 110 mounted with the vehicle antenna according to the embodiment of the present invention. FIG. 11 is an enlarged view of a circled region in FIG. As shown in FIG. 9, the air spoiler 110 is attached so as to follow the ceiling plate at the rear of the vehicle 100. The air spoiler 110 becomes a hollow body having a space inside by connecting and assembling the upper half casing 111 and the lower half casing 112 manufactured by resin molding by bonding or the like.

  FIG. 10 shows the antenna unit attached to the lower half casing 112 of the air spoiler. The antenna unit includes an analog radio antenna assembly 21 extending in the width direction of the vehicle along the inner side of the lower half casing 112 on the rear side of the vehicle, a digital TV antenna assembly 23 disposed on the right side of the lower half casing 112, and An amplifier 25 and a digital television / antenna assembly 22 and an amplifier 24 disposed on the left side of the lower casing 112 are provided. The analog radio antenna assembly 21 has a flat antenna element and a branch board 27 for branching the signal from the antenna element to the output of the left digital TV antenna assembly 22. The positions 22 and 23 can be adjusted.

  A digital television / antenna assembly 22 shown in FIG. 11 includes a vehicle antenna 10 having an element 11, an element base 19, and an antenna element substrate 26, and is rotatably supported by an analog radio / antenna assembly 21 via a bracket 31. ing. The signal received by the digital TV / antenna assembly 22 is amplified by an amplifier 24 and output to a tuner (not shown).

  The vehicular antenna according to the present invention is formed by printing conductive ink / paste. In order to reduce the printing area, the bandwidth of the antenna characteristics is narrowed by providing mesh-like cutouts and cutouts. The printing area is reduced without optimization and the printing area is optimized. The first step in optimizing the printing area is to use a mono-element antenna that has freedom in element shape, and compare a solid antenna without a mesh cutout hole with an antenna with a mesh cutout hole. went. Next, in order to further optimize the printing area, the second stage of optimization goes through the examination stage based on the notch shape, and then the third stage of optimization uses the vehicle antenna with a combination of mesh and notch. A reduction in printing area of about 70% with respect to the solid antenna was realized.

  FIG. 3 shows a reference configuration of a vehicle antenna that is a reference for understanding the embodiment of the present invention. The element 11 includes the mesh portion 13 having the rectangular shape shown in FIG. 2, the patterns of the GND 15 and 16, and the element 11. The feed point 14 which connects GND15 and 16 is shown. A characteristic feature of this reference configuration is that a mono-element antenna having a degree of freedom in the element shape is adopted and a mesh-like element having a square cutout hole is formed. Specifically, the increase and decrease in the bandwidth between the mesh-like element and the solid pattern in which the pitch and the opening size, which are the intervals between the squares of the mesh-like element, were sequentially changed were quantified by the bandwidth ratio.

  First stage of optimization: FIG. 4 shows the characteristics of the area ratio and the bandwidth ratio with the opposed pattern in the vehicle antenna 20 of FIG. 3, the horizontal axis shows the area ratio and the vertical axis shows the bandwidth ratio. ing. As a result of the investigation, it was found that even if the area ratio was reduced by 20%, the bandwidth ratio was only reduced by several percent, and the mesh area could reduce the printing area. In addition, almost no bandwidth was observed due to the change of the pitch, and it was found that the reduction of the printing area due to the change of the aperture size affects the reduction of the bandwidth at each pitch. Therefore, we decided to verify the second stage of optimization.

  Second stage of optimization: FIG. 5 shows a reference configuration of a vehicular antenna to be used as a reference for understanding the embodiment of the present invention, and FIG. 5A shows a distance Y cut away from the side opposite to the feeding point. A notch is created by the step, and the notch is further expanded by a distance X. The edge length of the long side L in FIG. 5A is 120 mm, and the edge length of the short side W is 30 mm. FIG. 5B shows a schematic diagram of the resonance state due to the current distribution of the element with a solid pattern, and FIG. 5C shows a schematic diagram of the resonance state of the element having a notch. As shown in FIGS. 5 (B) and 5 (C), the component contributing to resonance becomes a long side edge portion even in a solid pattern or notched state, and even if a notch is provided as shown in FIG. 5 (C). The current distribution in that part does not change greatly. However, it was also found that when a notch larger than FIG. 5C is provided, the resonance component of another mode becomes stronger than the main resonance component.

  6 shows the characteristics of the bandwidth reduction ratio according to the X-direction dimension and the Y-direction dimension in the vehicle antenna of FIG. 5, and the horizontal axis shows the X-direction dimension, the vertical axis shows the Y-direction dimension, and the pattern in the graph. Shows the bandwidth reduction ratio. In FIG. 6, there is no decrease in the bandwidth when the X-direction dimension is 5.0 mm at the lower left corner and the Y-direction dimension is 50.0 mm. A width reduction is observed, and the resonance component of another mode becomes stronger than the main resonance component. In the figure, the pattern bandwidth reduction ratio of the X direction dimension of 25.0 mm and the Y direction dimension of 90.0 mm surrounded by circles is 1.0, and a preferable shape dimension is obtained from the result of the current distribution.

  Third stage of optimization: FIG. 8 shows the characteristics of the bandwidth ratio to the area ratio in the vehicular antenna of FIG. In FIG. 8, when a mesh element (pitch 6 mm, opening size 4 mm) and a notch (25 × 90 mm) are combined, the area ratio can be reduced to 70% of the solid pattern even if the area ratio is reduced. It can be seen that the print area of the conductive ink can be reduced by combining mesh elements and notches. Therefore, it is possible to reduce the printing cost by reducing the amount of silver paste used as the conductive ink.

  As described above, by using the vehicle antenna according to the present embodiment, a conductive foil without reducing the performance of the antenna characteristics by providing a mesh-shaped hole or notch in the wide monopole antenna. The vehicular antenna with a reduced area and the amount of conductive ink used can be realized. In the present embodiment, the optimization is performed in the first to third stages. However, the present invention is not limited to this combination, and the first and second stages may be used.

  10, 20, 30 Vehicle antenna, 11 element, 12 notch, 13 mesh, 14 feeding point, 15, 16 GND, 17, 18 PET film, 19 element base, 21 analog radio antenna assembly, 22, 23 Digital TV / antenna assembly, 24, 25 amplifier, 26 antenna element board, 27 branch board, 31 bracket, 100 vehicle, 110 air spoiler, 111 upper half casing, 112 lower half casing.

Claims (4)

In vehicle antennas,
A rectangular conductor forming a monopole antenna;
Anda feed point is connected to one end of the rectangular type conductor,
The rectangular conductor is
A notched portion in which the conductor is notched in the long side direction from the short side on the other end side;
Provided the feed point side of the notch includes a mesh portion having a plurality of cutouts holes, and is formed by printing with conductive ink, formed on the mesh portion and the notch is on the same plane vehicle antenna, characterized in that it is. The vehicle antenna according to claim 1, wherein
Provided in the exterior of the vehicle,
The vehicle antenna according to claim 1, wherein the rectangular conductor is printed on a plastic film. In vehicle antennas,
A rectangular conductor forming a monopole antenna;
Anda feed point is connected to one end of the rectangular type conductor,
The rectangular conductor is
A notched portion in which the conductor is notched in the long side direction from the short side on the other end side;
It provided the feed point side of the notch includes a mesh portion having a plurality of cutouts holes, and is formed by a conductive foil, the mesh portion and the cutout portion is formed on the same surface An antenna for a vehicle. The vehicle antenna according to any one of claims 1 to 3,
Each cutout holes of the mesh portion may have a polygonal shape having a length of a predetermined side,
The rectangular type conductor the notch provided on the other end side of has a predetermined length in the short side direction of the other end, a length extending from the other end in the long side direction, and
A vehicle antenna characterized in that each length is set within a range that does not cause a deterioration in bandwidth of antenna characteristics.

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