JP4700660B2 - Vehicle antennas affixed to glass where conductive wires are placed - Google Patents

Description

  The present invention relates to a vehicular antenna, and more particularly to a vehicular antenna that can be improved in VSWR characteristics and gain characteristics and can have a wide band even when attached to glass on which conductive wires are arranged.

  The antenna provided on the glass of the vehicle is roughly divided into a glass antenna and a film antenna. The glass antenna is obtained by printing antenna wires on glass in advance. In the film antenna, an antenna element is provided on an adhesive film, and the film is adhered to glass. Some vehicle antennas include an adhesive layer provided on an antenna element provided on a film, and after being attached to glass, the film is peeled off so that only the antenna element remains on the glass. Hereinafter, in the present specification, the term “vehicle antenna” is described as including a film antenna, an antenna having a structure in which only an antenna element is left, and the like. There are various types of vehicle antennas for each glass to be pasted, such as for windshields, rear glasses, and side glasses.

  In particular, in the case of a vehicle antenna for a rear glass, the defogger heat ray arranged on the rear glass affects the antenna element, which deteriorates the antenna characteristics. For this reason, for example, an antenna having an antenna pattern in which an antenna element is arranged so as to avoid heat rays has been developed, such as the antenna disclosed in Patent Document 1. In addition, in order to increase the bandwidth, etc., an antenna (Patent Document 2) in which a parasitic element is arranged in the vicinity of a loop antenna, or two antenna elements along a glass peripheral part so as to be U-shaped or L-shaped. An antenna (Patent Document 3) arranged in a similar manner has also been developed.

Design Registration No. 1294914 JP 2007-67884 A JP-A-4-132401

  The vehicular antenna is attached to the glass, so it must not interfere with the driver's field of view, and even if it does not obstruct the field of view, it must be avoided. Therefore, a simple and small antenna pattern has been desired. However, in the case of a conventional antenna for a vehicle, particularly in the case of a rear glass, a complicated antenna pattern has been formed in order to avoid the influence of heat rays. In addition, since the parasitic element is provided, the antenna pattern may be complicated or the number of parts may increase.

  Furthermore, when a coaxial cable is connected to the antenna element via a pickup or the like, if the coaxial cable is routed parallel to the antenna element, the antenna element will be affected by the coaxial cable. On the other hand, it was necessary to route vertically. More specifically, for example, as shown in FIG. 1, in the case of the configuration disclosed in Patent Document 2, a pickup in which a coaxial cable 3 is connected to power supply terminals 2 and 2 provided in the loop antenna 1. 4 is fixed. Here, when the antenna pattern in the horizontal direction of the loop antenna 1 and the coaxial cable 3 are arranged in parallel, the antenna element is adversely affected. Therefore, the coaxial cable 3 is bent 90 degrees from the pickup and routed in the vertical direction. . In particular, when the film antenna having such a configuration is attached to the rear glass, the coaxial cable that intersects perpendicularly to the heat wires arranged in the horizontal direction is very disturbing to the driver. Further, since the parasitic element 5 needs to be provided, the antenna pattern is complicated.

  Furthermore, in the case of a configuration like the antenna disclosed in Patent Document 3, the antenna element has to be disposed along the peripheral edge of the glass of the vehicle, and the degree of freedom of installation is low. In addition, the structure is easily affected by heat rays.

  In view of such circumstances, the present invention provides a vehicular antenna that has a simple configuration and can improve the VSWR characteristics and gain characteristics and increase the bandwidth even when used by being attached to glass on which conductive wires are arranged. It is what.

  In order to achieve the above-described object of the present invention, a vehicle antenna according to the present invention includes a power feeding unit including a hot side terminal and a ground side terminal, a hot side antenna pattern extending from the hot side terminal, and a ground extending from the ground side terminal. An antenna pattern that is arranged in a loop from the power feeding portion, and is configured so that the hot-side antenna pattern is arranged substantially in parallel with the conductive lines and in the approximate center between the conductive lines, An antenna pattern configured to be disposed so that the side antenna pattern has at least a portion substantially parallel to the conductive line and a portion that intersects the conductive line substantially perpendicularly.

  Here, the hot-side antenna pattern and the ground-side antenna pattern may be arranged so that their tip portions are aligned in a direction substantially perpendicular to the conductive wire.

  The antenna pattern may be a substantially quadrilateral.

  Furthermore, the power feeding unit may be arranged at a corner of the quadrilateral antenna pattern.

  Further, the arrangement direction of the hot-side terminal and the ground-side terminal of the power feeding unit may be configured to be substantially parallel to the conductive wire.

  Further, the ground side antenna pattern may be configured such that the tip portion thereof is disposed on the conductive line.

  Furthermore, the ground side antenna pattern may be configured so as to have a virtual loop shape together with the conductive line.

  The vehicular antenna of the present invention has a simple configuration with only a loop antenna pattern, is less obstructive to the driver, has a high degree of freedom in installation position, and improves the VSWR characteristics and gain characteristics and widens the bandwidth. There is an advantage that you can.

  The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 2 is a schematic plan view for explaining the vehicle antenna of the present invention. The vehicular antenna of the present invention is affixed to a glass on which a defogger heat ray is disposed. Note that the vehicle antenna of the present invention can be applied not only to heat rays but also to cases where the conductive wires such as other antenna wires are attached to the glass. The present invention is not limited to the rear glass but can be applied to a side glass or the like. Hereinafter, in this specification, it demonstrates focusing on a heat ray as a conductive wire. In addition, the vehicle antenna of the present invention is not limited to a film antenna, but an adhesive layer is provided on the antenna element provided on the film, and the film is peeled off after being attached to glass so that only the antenna element remains on the glass. It can also be applied to things.

  As shown in the figure, the vehicle antenna of the present invention is mainly composed of a power feeding unit 10 and an antenna pattern 13. The power supply unit 10 includes a hot side terminal 11 and a ground side terminal 12, and is connected to an external device (not shown) via a pickup 30 and a cable 40. In the illustrated example, the arrangement direction of the hot-side terminal 11 and the ground-side terminal 12 of the power supply unit 10 is configured to be substantially parallel to the heat wire 20 of the defogger. Note that the glass of a vehicle is generally composed of a curved surface rather than a flat surface, and the heat rays are arranged so as to look straight when viewed from the driver side, and are arranged curved rather than straight on the glass surface. It is common. Therefore, the term “substantially parallel” in this specification includes a configuration in which the heat ray 20 is arranged so as not to intersect with the curved heat wire 20 as described above.

  The antenna pattern 13 is an antenna element arranged in a loop from the power feeding unit 10. In the illustrated example, the antenna patterns are arranged in a substantially quadrangular shape, more specifically, in a square shape. The antenna pattern of the vehicle antenna of the present invention is not limited to a square, and may be a rectangle. The antenna pattern 13 includes a hot side antenna pattern 14 extending from the hot side terminal 11 and a ground side antenna pattern 15 extending from the ground side terminal 12. Thus, in the vehicular antenna of the present invention, the antenna pattern 13 has a configuration different from that of a so-called loop antenna having a complete loop shape, and has a configuration in which a part of the loop is cut and removed. .

  The hot-side antenna pattern 14 is configured to be arranged substantially in parallel with the defogger hot wire 20. Further, the hot-side antenna pattern 14 is configured so as to be disposed at the approximate center between the hot wires. In this specification, “substantially the center” is not limited to being located at the exact center between the hot wires, and the hot antenna pattern is separated from each hot wire to the extent that it is not affected by the hot wires as much as possible. It is also intended to be configured to be arranged at a different position. The length of the hot antenna pattern 14 is adjusted to have an electrical length of λ / 4 wavelength, where λ is the wavelength of the target frequency. However, since the vehicular antenna of the present invention is a broadband antenna, there is no strict target frequency, and the effect of the shortening rate (wavelength shortening rate) due to glass so that λ is included in any of the frequency bands to be used. The length may be determined in consideration of The shortening rate is a rate at which the propagation speed is slowed and the wavelength is shortened due to the influence of the insulator when the radio wave propagates to the insulator such as glass.

  On the other hand, in the illustrated example, the ground-side antenna pattern 15 extends downward from the ground-side terminal 12 in the vertical direction, refracts 90 degrees to the right, extends substantially parallel to the heat ray 20, and further refracts 90 degrees upward and vertically. It is configured to extend upward in the direction and to reach the vicinity of the tip of the hot-side antenna pattern 14. That is, the ground side antenna pattern 15 is configured to have a portion substantially parallel to the heat wire 20 and a portion intersecting the heat wire 20 substantially perpendicularly. And the front-end | tip part of the hot side antenna pattern 14 and the front-end | tip part of the ground side antenna pattern 15 are comprised so that it may be arrange | positioned in the position which aligns in the direction substantially perpendicular | vertical to a heat ray.

  When the vehicular antenna configured as described above is attached to glass, first, the hot-side antenna pattern 14 is positioned so as to be substantially parallel to the defogger hot wire 20 and at the approximate center between the hot wires 20. At this time, the arrangement direction of the hot-side terminal 11 and the ground-side terminal 12 is substantially parallel to the heat wire 20, and the power feeding unit 10 comes to the approximate center between the heat wires 20.

  Then, the pickup 30 is attached in accordance with the positions of the hot side terminal 11 and the ground side terminal 12. A cable 40 such as a coaxial cable extending from the pickup 30 is routed substantially parallel to the hot-side antenna pattern 14 as illustrated. In the vehicular antenna of the present invention, since the power feeding unit 10 is arranged at the corner of the quadrangular loop antenna pattern, the antenna pattern 13 and the cable 40 are not arranged in parallel. Therefore, the hot antenna pattern 14 is not affected by the cable 40 as in the illustrated example, and the cable 40 can be routed substantially parallel to the hot wire 20, that is, in the same direction as the hot wire 20. Therefore, it is possible to prevent the cable 40 from becoming an obstacle to the driver.

  Here, a change in characteristics when the vehicle antenna shown in FIG. 2 is shifted up and down with respect to the heat ray will be described with reference to FIG. FIG. 3 is a graph of frequency vs. VSWR characteristics when the hot-side antenna pattern of the vehicular antenna is arranged 10 mm above and below the center between the hot wires. As can be seen from the graph of FIG. 3, it can be seen that the average characteristic of the VSWR is best in the state of being arranged in the center as compared with the case where the hot antenna pattern is shifted upward or downward. In addition, since it should just be arrange | positioned in the approximate center between heat rays, the freedom degree of arrangement | positioning is also high.

  Next, another example of the vehicle antenna of the present invention will be described. As described above, in the example shown in FIG. 2, the ground-side antenna pattern 15 is configured to intersect three heat rays 20 on the right side of the loop-shaped antenna pattern 13. However, the vehicle antenna of the present invention is not limited to this. FIG. 4 is a schematic plan view for explaining another example of the vehicle antenna of the present invention. In the figure, portions denoted by the same reference numerals as those in FIG. 2 generally represent the same constituent elements, and thus redundant description is omitted. As shown in FIG. 4, the configuration may be such that the tip of the ground-side antenna pattern 15 is disposed on the heat wire 20 without intersecting the heat wire 20 on the right side of the loop-shaped antenna pattern 13. As illustrated, the ground-side antenna pattern 15 is configured so as to have a virtual loop shape together with the heat ray 20. That is, the ground-side antenna pattern 15 passes through the heat ray 20 from the tip thereof and passes through the portion where the heat ray 20 intersects the ground-side antenna pattern 15 (on the left side of the loop-shaped antenna pattern 13). Constitutes a virtual loop shape together with the hot wire 20.

  Furthermore, the loop-shaped antenna pattern 13 may be a U-shaped loop. FIG. 5 is a schematic plan view for explaining still another example of the vehicle antenna of the present invention. In the figure, portions denoted by the same reference numerals as those in FIG. 2 generally represent the same constituent elements, and thus redundant description is omitted. As shown in FIG. 5, the entire right side of the loop-shaped antenna pattern 13 may be removed. Also in this case, the front end portion of the hot-side antenna pattern 14 and the front end portion of the ground-side antenna pattern 15 are configured to be arranged at positions aligned in a direction substantially perpendicular to the heat rays.

  Furthermore, in the above-described illustrated example, the example in which the feeding portion is arranged at the corner of the quadrilateral antenna pattern, more specifically, the upper left corner, is shown, but the present invention is not limited to this, and FIG. As shown, it may be arranged near the center of the upper side of the quadrilateral antenna pattern 13. However, in this case, if the cable 40 is routed substantially parallel to the hot wire 20, the cable 40 is arranged in parallel to the antenna pattern 13. Therefore, in order to avoid the influence of the cable, the cable 40 is perpendicular to the hot wire 20. It is preferable to draw around. FIG. 6 shows an example in which the antenna pattern 13 is rectangular, and the tip of the ground antenna pattern 15 is arranged on the right side of the tip of the hot antenna pattern 14. However, the present invention is not limited to this, and the ground-side antenna pattern 15 may be configured such that the front end portion thereof is disposed further to the left than the front end portion of the hot-side antenna pattern 14. Further, the tip of the ground side antenna pattern 15 may extend further upward than the hot side antenna pattern 14 from the state of FIG. Furthermore, the tip of the ground-side antenna pattern 15 may extend from the state to the left, and the hot-side antenna pattern 14 may be covered with the ground-side antenna pattern 15. The same applies to an example in which the power feeding unit is disposed at the corner of the quadrilateral antenna pattern.

  In the illustrated example described above, the arrangement direction of the hot-side terminal 11 and the ground-side terminal 12 of the power supply unit 10 is substantially parallel to the heat wire 20, but the present invention is not limited to this, and FIG. As shown in FIG. 5, the arrangement direction of the hot-side terminal 11 and the ground-side terminal 12 of the power feeding unit 10 may be configured to be substantially perpendicular to the heat wire 20. However, in this case, since an electronic circuit such as an amplifier circuit that may be provided in the pickup 30 may be affected by the heat ray 20, it is preferable to perform shielding or the like.

  Furthermore, in the above-described illustrated example, the loop-shaped antenna pattern is configured based on a quadrilateral, but the present invention is not limited to this. That is, the antenna pattern of the vehicular antenna of the present invention is such that the hot-side antenna pattern is disposed substantially parallel to the heat rays, the ground-side antenna pattern is substantially parallel to the heat rays, and the portion intersecting the heat rays substantially perpendicularly. If it has at least, it does not necessarily need to be comprised on the basis of a quadrilateral, for example, as shown in FIG. 8, you may comprise in a curve loop shape.

  Hereinafter, the results of measuring the VSWR characteristics of the vehicle antenna of the present invention will be described. In addition, although the dimension of the antenna pattern, a frequency, etc. are shown concretely by the following description, these are an example to the last, and this invention is not limited to these specific dimensions, a frequency, etc.

  The width between the hot wires 20 arranged on the glass of the vehicle was 30 mm, and the shortening rate of the glass was 0.65. Further, the position where the vehicle antenna is arranged is set to a position 100 mm from the side flange of the vehicle. The antenna pattern 13 was a square pattern with a line width of 0.5 mm and a square of 90 mm, and the target frequency was set to around 540 Mhz.

  Based on this shape, the frequency vs. VSWR when the space (cut width) at the tip of the hot side antenna pattern 14 and the ground side antenna pattern 15 is changed to 1 mm, 5 mm, 10 mm, 30 mm, 60 mm, 75 mm, and 90 mm. A characteristic graph is shown in FIG. In addition, a 75 mm cut is the state of FIG. 4, and a 90 mm cut is the state of FIG. For comparison, there is no space at the tip of the hot-side antenna pattern 14 and the ground-side antenna pattern 15, that is, in a so-called loop antenna state, and when the right and lower sides of the ground-side antenna pattern 15 are removed. That is, the VSWR characteristics in the case of a so-called dipole antenna are also shown in FIG.

  As can be seen from the graph of FIG. 9, it can be seen that the VSWR characteristics of the vehicular antenna of the present invention are greatly improved from about 480 Mhz to about 650 Mhz as compared with the configuration of the loop antenna and the dipole antenna. When viewed in more detail, it can be seen that the average value of VSWR is suppressed to the lowest in the state shown in FIG. It can also be seen that the characteristics are greatly improved by cutting even 1 mm, and that the average VSWR characteristics are improved by using a loop-shaped antenna pattern as in the present invention, compared to the dipole antenna structure.

  Moreover, according to the vehicle antenna of this invention, it turned out that a gain characteristic is also improved and a broadband can be achieved.

  The vehicular antenna of the present invention is not limited to the illustrated examples described above, and it is needless to say that various modifications can be made without departing from the gist of the present invention.

FIG. 1 is a schematic plan view for explaining a conventional vehicle antenna. FIG. 2 is a schematic plan view for explaining the vehicle antenna of the present invention. FIG. 3 is a graph of frequency versus VSWR characteristics when the hot-side antenna pattern of the vehicular antenna of the present invention is arranged shifted up and down from the center between the hot wires. FIG. 4 is a schematic plan view for explaining another example of the vehicle antenna of the present invention. FIG. 5 is a schematic plan view for explaining still another example of the vehicle antenna of the present invention. FIG. 6 is a schematic plan view for explaining still another example of the vehicle antenna of the present invention. FIG. 7 is a schematic plan view for explaining still another example of the vehicle antenna of the present invention. FIG. 8 is a schematic plan view for explaining still another example of the vehicle antenna of the present invention. FIG. 9 is a graph of frequency versus VSWR characteristics when the space at the tip of the hot antenna pattern and the ground antenna pattern of the vehicle antenna of the present invention is changed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Power supply part 11 Hot side terminal 12 Ground side terminal 13 Antenna pattern 14 Hot side antenna pattern 15 Ground side antenna pattern 20 Hot wire 30 Pickup 40 Cable

Claims (7)

A vehicle antenna to be affixed to glass on which a conductive wire of a vehicle is disposed, the vehicle antenna is
A power feeding unit comprising a hot side terminal and a ground side terminal;
An antenna pattern that is arranged in a substantially loop shape from the feeding portion, and that includes a hot-side antenna pattern extending from the hot-side terminal and a ground-side antenna pattern extending from the ground-side terminal, and a tip of the hot-side antenna pattern It is arranged so as to be separated from the tip of the ground-side antenna pattern, and is arranged at a position that is so far away that the hot-side antenna pattern is not affected by the conductive lines , approximately parallel and at the approximate center between the conductive lines. An antenna pattern configured to be arranged to have at least a portion substantially parallel to the conductive line and a portion intersecting the conductive line substantially perpendicularly,
A vehicle antenna characterized by comprising:
  2. The vehicle antenna according to claim 1, wherein the hot-side antenna pattern and the ground-side antenna pattern are configured to be arranged at positions where their front end portions are aligned in a direction substantially perpendicular to the conductive wire. Vehicle antenna.   2. The vehicular antenna according to claim 1, wherein the antenna pattern is a substantially quadrilateral.   The vehicle antenna according to claim 3, wherein the power feeding portion is arranged at a corner of the quadrilateral antenna pattern.   5. The vehicle antenna according to claim 1, wherein an arrangement direction of the hot-side terminal and the ground-side terminal of the power feeding unit is configured to be substantially parallel to the conductive line. Vehicle antenna.   The vehicle antenna according to any one of claims 1 to 5, wherein the ground-side antenna pattern is configured such that a tip end portion thereof is disposed on a conductive wire.   The vehicle antenna according to any one of claims 1 to 6, wherein the ground-side antenna pattern is arranged so as to have a virtual loop shape together with a conductive line. .