JPH0113643B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a glass antenna for radio or TV reception in automobiles. 2. Description of the Related Art Conventionally, it has been known that a rear window glass of an automobile is provided with a plurality of anti-fog heating conductive wires and an antenna wire for radio or TV reception. For example, a plurality of medium wave antenna wires and one very high frequency antenna wire parallel to the horizontal plane are provided above the heating conductive wire, and these antenna wires are interconnected by the conductive wire. The one connected to is used. Such a glass antenna has an "8"-shaped directional characteristic in which the gain is minimum for radio waves arriving from the front and rear directions of the vehicle in the ultra-high frequency band, and the gain is maximum for radio waves arriving from the side. have. Therefore, depending on the direction of the vehicle, the S/N ratio deteriorates and noise increases. In order to improve such directivity characteristics and obtain omnidirectional characteristics, it is known that an auxiliary antenna is attached in parallel to the above-described group of antenna lines. The auxiliary antenna and the main antenna are connected to each other with phase matching or impedance matching so as to obtain omnidirectional characteristics. A glass antenna with such an auxiliary antenna can be tuned to exhibit almost omnidirectional characteristics in the ultra-high frequency band, but depending on the usage conditions, a dip point in the reception level may occur at a particular azimuth, or the reception level may become weak. Offset or uneven levels may occur. That is, this type of glass antenna is also supplied with received wave power by induction from a heating conductive wire attached in parallel with the glass antenna. For this reason, even if proper tuning is performed when designing a glass antenna to exhibit omnidirectional characteristics, the tuning point will shift if the induction state of the high-frequency signal from the heating conductive wire changes, resulting in the dip point as described above. occurs. In particular, it is known that the heating conductive wire feeder line has a large effect on the distortion of the directivity characteristics. Further, in the case of a so-called liftback type automobile in which the angle of inclination of the rear window with respect to the horizontal plane is smaller than that of a sedan type automobile, such distortion of the directivity characteristics may occur significantly. In view of the above-mentioned problems, the present invention aims to improve the directivity characteristics of a glass antenna to make it as close to circular as possible. The glass antenna of the present invention includes a plurality of heating conductive wires attached horizontally to the surface of an automobile window glass, and extending in an L-shape from a feeding point located near the side edge of the window glass. an L-shaped part extending horizontally from the power supply point, a horizontal part that is folded back from the horizontal part to the side of the heating conductive wire at the other side end of the window glass to the vicinity of the power supply point; and a main antenna line consisting of a folded portion extending horizontally. a first horizontal auxiliary antenna wire that closely faces the heating conductive wire and is coupled to the folded portion of the main antenna wire in the vicinity of the vertical center line position of the window glass; and both ends of the horizontal wire. The antenna further includes a second horizontal auxiliary antenna wire, which is connected to a substantially midpoint thereof and a position of the horizontal portion of the main antenna wire at a position deviated from the centerline position via a connecting line formed by bending the main antenna wire. The L-shaped portion of the main antenna wire extends close to and parallel to the second auxiliary antenna wire to the vicinity of the center line. In addition, in order to compensate for the dip part of the directivity characteristic of the main antenna wire,
The heating apparatus further includes an auxiliary antenna element connected to the heating conductive wire. In the above configuration, a high-performance antenna with almost no directionality can be obtained using the antenna wire, but depending on the type of car, the mounting angle of the window glass with respect to the horizontal plane changes, resulting in a decrease in sensitivity depending on the reception direction. Sometimes. When the auxiliary antenna element is connected to the heating conductive wire, such a dip in directivity is compensated for, and a substantially omnidirectional antenna is obtained. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a front view and an electric circuit diagram of a rear window glass of an automobile showing an embodiment of the present invention. As shown in FIG. 1, a heating conductive wire group 2 for preventing fogging is provided on a rear window glass 1 of an automobile, and these are connected to a battery 3 through busbars 4, 5, 6 and power supply lines 20, 21. A heating current is applied from the An antenna wire group 7 is provided above the heating conductive wire group 2, and the received output is led out to a preamplifier 9 via a coaxial cable 16 coupled to a feeding point 8.
In the preamplifier 9, the received signals in the AM wave band and the FM wave band are divided into bands and amplified, and then sent to the tuner. In order to effectively utilize the induced power from the heating conductive wire group 2, the power supply lines 2 are connected between the heating conductive wire group 2, the battery 3, and the grounding point (vehicle body).
0 and 21 are interposed with a high frequency choke coil 10 having extremely high resistance in the radio frequency band. Further, a decoupling capacitor 11 is connected between the line and the ground point to prevent noise on the power line from being mixed into the received signal. The antenna wire group 7 includes a main antenna consisting of three mutually parallel antenna wires 12a, 12b, and 12c, and auxiliary antenna wires 13a and 13b coupled to the main antenna. The central main antenna line 12b extends horizontally from the feeding point 8, and its tip side is bent downward and continues to the end of the lower main antenna line 12c. The upper main antenna line 12a extends upward from the feeding point 8, is further folded back in parallel, and reaches approximately the center of the window glass 1. That is, the main antenna filaments 12a, 12b, and 12c constitute an L-shaped portion, a horizontal portion, and a folded portion, respectively. The auxiliary antenna line 13a is provided above the main antenna line 12a, and the main antenna line 13a is provided above the main antenna line 12a.
2a and are closely opposed to each other over a predetermined length. The auxiliary antenna wire 13a is arranged almost symmetrically with respect to the central axis 14 (dotted chain line) of the window glass 1, and the main antenna wire Connecting line 15 parallel to the strip 12b and bent at both ends
are connected via. Further, the lower auxiliary antenna 13b is disposed between the lower main antenna filament 12c and the heating conductive wire group 2, and is closely opposed to the heating conductive wire group 2. This auxiliary antenna wire 13b
is coupled to the main antenna line 12c at the central axis 14 of the window glass 1. The auxiliary antenna wire 13b is provided for the purpose of transmitting the received waves induced from the heating conductive wire group 2 to the main antenna wire 12c side. Therefore, by matching the phase of the received waves, the auxiliary antenna wire 13b
It is preferable to combine the main antenna wire 12c with the main antenna wire 12c, and it has been experimentally confirmed that a preferable result can be obtained when the two are combined at a connecting point A near the central axis 14 of the window glass 1, as shown in FIG. It is being In this preferred bonding state, the bonding point A
is considered to correspond to the zero point of the potential distribution of the antenna placed in the received electric field. It is preferable that the upper auxiliary antenna wire 13a is also coupled to the main antenna wire 12b by matching the phase (or impedance), and the output is taken from approximately the midpoint of the auxiliary antenna wire 13a, and this is shown in FIG. Matching can be achieved by supplying the signal to a coupling point B shifted from the center position of the main antenna wire 12b, as shown in FIG. It has been experimentally confirmed that the position of point B is a tuning point that has a great influence on improving the directivity characteristics of the antenna and obtaining substantially circular omnidirectional characteristics in all azimuth angles. The upper auxiliary antenna line 13a has the function of supplying received power to the main antenna line 12b as described above, and also has the function of supplying received power to the main antenna line 12b.
It is thought that it also has the function of giving induced power to 2a. Therefore, the opposing length of the auxiliary antenna filament 13a and the main antenna filament 12a has a great influence on the directivity characteristics of the antenna. That is, from the tip of the main antenna filament 12a to the auxiliary antenna filament 1
It has been experimentally confirmed that an optimal value exists for the horizontal distance to the signal extraction point (midpoint) of 3a. Preferred dimensions of the antenna pattern shown in FIG. 1 are as shown in Example 1 or Example 1 in the table below. In the table below, a and b are the distances from the central axis 14 of the window glass 1 to both ends of the auxiliary antenna filament 13a, c is the distance from the tip of the main antenna filament 12a to the central axis 14, and d is the central axis 14. The distance from to the connection point B on the main antenna line 12c, e and f are the distances from the central axis 14 to both ends of the auxiliary antenna line 13b,
g is the distance between the top of the heating conductive wire group 2 and the auxiliary antenna wire 12c, and h, i, j, and k are the auxiliary antenna wire 13b and the main antenna wire 12c, 12, respectively.
b is the vertical spacing between the connecting line 15 and the auxiliary antenna filament 13a, and l is the spacing between the auxiliary antenna filament 13a and the main antenna filament 12a.

[Table] Heating conductive wire group 2, bus bars 4, 5, and 6, each antenna wire group 7, and feeding point 8 are made of conductive paste made of fine silver particles, low-melting glass powder, etc. in an organic solvent. is screen printed on window glass 1 and further baked. When used in a sedan-type passenger car, the antenna pattern described above exhibits nearly circular omnidirectional characteristics with no dip points in the domestic FM broadcast band of 70 to 90 MHz. However, when this is used in a so-called lift-back type passenger car, where the angle of inclination of the rear window glass with respect to the horizontal plane is smaller than that of a sedan type, the antenna directional characteristic curves shown in Figs. A dot appears. Further, even if the antenna pattern is tuned so as to obtain an almost circular omnidirectional characteristic, a dip point may occur depending on how the feeder lines 20 and 21 are routed. In this embodiment, in order to eliminate such distortion of the directional characteristics, the heating conductive wire group 2 is used as shown in FIG.
An auxiliary antenna wire 17 is attached to the antenna. In the embodiment shown in FIG. 1, the auxiliary antenna wire 17 is extended upward from the generating line 5 of the heating conductive wire group 2, bent at a substantially right angle near the upper side of the window glass 1, and further extended laterally. One end of this auxiliary antenna wire 17 is an open end. 2-4 show another embodiment of the auxiliary antenna. In FIG. 2, the auxiliary antenna wire 17 is extended upward from the generatrix of the heating conductive wire group 2 to near the upper side of the window glass 1, bent at a substantially right angle, and extended laterally. In FIG. 3, auxiliary antenna wires 18a and 18b with one end open are connected to the bus bars 4 and 6, respectively, and are placed along feeder lines 20 and 21. In this case, two conductor parallel wires or stranded electric wires are used as the feeder lines 20 and 21, and one conductor of each electric wire can be used as a feeder wire, and the other conductor can be used as an auxiliary antenna wire. Note that only one of the auxiliary antenna lines 18a and 18b may be used. In FIG. 4, an auxiliary antenna wire 17 is extended below the heating conductive wire group 2 along the bottom side of the window glass 1, with one end being an open end and the other end being connected to the bus bar 5. According to each of the above-described embodiments, the auxiliary antenna filament 17 or the auxiliary antenna wires 18a and 18b added to the heating conductive wire group 2 can significantly improve the distortion of the directivity characteristics of the antenna. 5 to 7 are antenna directivity characteristic diagrams corresponding to the embodiments shown in FIGS. 1 to 3, respectively. Figures 5 to 7
As shown by the dotted line in the figure, there is no dip point in the directional characteristics, and an antenna with nearly circular omnidirectional characteristics can be obtained. As described above, in the present invention, since the auxiliary antenna element is connected to the heating conductive wire, the receiving function of the heating conductive wire as an antenna can be enhanced.
It is possible to obtain a glass antenna with nearly circular omnidirectional characteristics without dip points or irregularities in reception level at specific azimuth angles.

[Brief explanation of drawings]

Fig. 1 is a front view and electrical circuit diagram of a rear window glass of an automobile showing one embodiment of the present invention, and Figs. 2 to 4 are a front view and electrical circuit diagram similar to Fig. 1 showing different embodiments. The circuit diagrams and FIGS. 5 to 7 are directional characteristic diagrams of the antennas of the embodiments shown in FIGS. 1 to 3, respectively. In addition, in the symbols used in the drawings, 1...
...Rear window glass, 2...Group of heating conductive wires, 7...
...Antenna wire group, 17...Auxiliary antenna wire,
18a, 18b...Auxiliary antenna wires.

Claims (1)

[Scope of Claims] 1. A plurality of heating conductive wires attached horizontally to the surface of an automobile window glass, and extending in an L-shape from a power feeding point located near the side edge of the window glass. an L-shaped part extending horizontally from the power supply point, a horizontal part that is folded back from the horizontal part to the side of the heating conductive wire at the other side end of the window glass to the vicinity of the power supply point; a main antenna strip consisting of a folded portion extending horizontally; and a main antenna strip that closely opposes the heating conductive strip and is coupled to the folded portion of the main antenna strip in the vicinity of the vertical center line position of the window glass. the first horizontal auxiliary antenna filament, and a connecting line formed by bending both ends of the horizontal filament to connect the approximately midpoint thereof to a position deviating from the center line position of the horizontal portion of the main antenna filament; and a second horizontal auxiliary antenna wire connected thereto, wherein the L-shaped portion of the main antenna wire extends close to and parallel to the second auxiliary antenna wire to the vicinity of the center line. A glass antenna, further comprising: an auxiliary antenna element connected to the heating conductive wire in order to compensate for a dip in the directivity characteristic of the main antenna wire.