JPH0242802A - Window glass antenna for vehicle - Google Patents

Abstract

PURPOSE:To obtain a feeder line, with which gain is not lowered even in case of a corner feeding system and loss goes to be low even when wiring is executed separately from a glass edge, by causing the feeder filament to be the strip conductor of specified line width. CONSTITUTION:A feeder filament 13 to connect an antenna element 11, which is provided in a rear window glass 1, and a feeding terminal 15 in a corner part is formed by the thick strip conductor, whose width is >=3mm, along the dge of the glass 1. Thus, even in case of the corner feeding system there is no loss of the gain and even when the wiring is not executed to be closed to a window frame but enough separately from the glass edge, a characteristic impedance to be matched with a feeder cable can be given to the feeder of the low loss. By this separate wiring, interruption can be prevented from being generated by corrosion or electro-corrosion due to moisture, permeates weather strip or adhesive agent to be interposed between the window frame and glass edge.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a window glass antenna for automobiles that uses window glass as an insulator.

[Summary of the invention]

By directing the received output of the antenna element provided on the window glass surface to the power supply terminal at the glass corner through the feeder wire made of a thick solid conductor, the feeder wire can be transmitted from the glass edge (window frame). An automotive window glass antenna that achieves high reception sensitivity while ensuring compatibility with the feeder cable connected to the power supply terminal at a sufficient distance and eliminating the risk of disconnection at the joint between the glass edge and window frame. It is.

[Conventional technology]

It is known that a patterned conductor for an antenna for radio or TV reception is provided on the window glass of an automobile along with heater strips for defogging. In this type of automobile window glass antenna, the conductor pattern is tuned so as to obtain neglect-direction characteristics in order to minimize fluctuations in reception gain due to changes in the direction of travel of the automobile. Therefore, the power feeding point (current collection point) is generally located at the center along the top edge of the window glass.
It is a center feeding type with a conductor pattern arranged approximately symmetrically on the left and right sides of the feeding point.

However, in the case of center feeding, the feeder cable inside the vehicle from the antenna to the tuner must be routed to the center of the top or bottom of the window glass, which is disadvantageous in terms of implementation. That is, if the power supply terminal is located at the upper or lower corner of the window glass, the wiring length will be considerably shortened, and the connector between the feeder cable and the power supply terminal will also be less noticeable.

For this reason, a single wire conductor extending from the center current collection point of the antenna conductor to the power feeding terminal at the corner of the window glass is formed on the glass surface and used as a feeder wire.

[Problem to be solved by the invention]

The characteristic impedance of the single wire aerial feeder line at -i is several hundred ohms, which is not matched with the coaxial feeder cable of, for example, 50 ohms, which is connected to the power supply terminal.

For this reason, in ultra-high frequency bands such as FM broadcasting, there is a drawback that a drop of about 10 dB occurs compared to the case where a coaxial feeder cable is directly connected to the center current collection point of the antenna conductor.

Japanese Patent Application Laid-Open No. 52-110550 discloses that a feeder conductor extending from the center of the glass to the corner is connected to an automobile window frame (
(earth), ie, along the glass edge, thereby adjusting the characteristic impedance and providing a low loss line matched to the feeder cable to reduce the gain drop.

However, an adhesive or rubber weather strip is interposed between the flange of an automobile window frame and the window glass, and in order to obtain the characteristic impedance adjustment effect described above, it is necessary to attach the feeder wire to the adhesive. Alternatively, it is necessary to route the wire closer to the edge so that it goes inside the weather strip. In such an arrangement, over a long period of time,
There is a risk that the feeder wire may break due to electrolytic corrosion caused by moisture seeping into the strip or corrosion caused by the adhesive between the window flange and the glass.

In view of this point, it is an object of the present invention to provide a feeder wire that does not cause a decrease in gain even if it is of a corner feeding type, and that functions as a low-loss feeder wire even if it is wired at a considerable distance from the glass edge.

[Means to solve the problem]

The window glass antenna of the present invention includes an antenna element conductor formed on a window glass surface, and a feeder wire that leads a received signal of the antenna element conductor to a power feeding terminal in a corner of the glass, and the feeder wire is a strip conductor having a line width of 3 mm or more along the edge of the window glass.

[Effect]

By increasing the width of the feeder wire, a low-loss feeder line with a characteristic impedance that matches the feeder cable can be obtained without having to wire it close to the window frame (glass edge), which is a ground conductor. Adhesive or rubber weather strips are interposed between the window frame and the glass edge, but by wiring the feeder wires far enough away from the edges to prevent them from entering this area,
There is no risk of disconnection due to corrosion or galvanic corrosion.

〔Example〕

FIG. 1 shows a front view of a rear window glass of an automobile to which the present invention is applied. In the middle area of the rear window glass 1, a large number of defogging heater lines 2 are formed in parallel by printing and firing.

Both ends of each heater wire 2 are connected to a power supply bus 3.4, and a heating current is passed from the battery 5 through the switch 6. Note that the heater wire 2 may be divided into two groups, upper and lower, and a folded power feeding type may be used.

The heater wire 2 is also used as an AM receiving antenna. For this reason, choke coils 8a and 8b, which are magnetically coupled to each other, are interposed in the middle of the feeder lines 7a and 7b connected to the mother vA3.4 to increase the ground impedance of the heater wire 2 in the radio band. These choke coils 8a, 8b
By making it a negative coupling, the magnetic saturation level is lowered and the core is made smaller. A capacitor 10 connected to one end of the choke coil 8a is for decoupling to absorb power supply noise.

A single wire antenna element II is formed above the heater filament 2. This antenna element 11 has a total length of about 1,200 mm and is tuned to the FM broadcast band, but by placing it close to the heater wire 2 at a distance of about 5 mm, the AM wave received by the heater wire 2 can be adjusted. I am also receiving guidance.

A current collection point tta approximately in the middle of the antenna element 11 is coupled to one end of a horizontal feeder line 13 along the upper side of the window glass l via a vertical coupling vA12. The other end of the feeder wire 13 extends to the corner of the window glass 1, and is further coupled to an antenna feed terminal 15 via a vertical coupling line 14.

A coaxial feeder cable (not shown) is connected to the power supply terminal 15 for supplying a received signal to the tuner.

These antenna elements 11, coupling wires 12, 14, feeder lines 13, and feeding terminals 15 are also formed on the glass surface by printing and firing.

As shown in the detailed view of FIG. 2, the feeder line 13 is placed on the top edge of the glass so that it does not come in contact with the adhesive 16 or rubber weather strip that is used when attaching the rear window glass l to the window frame of an automobile. 13-2 from Etsuji la
They are formed in a 5 mm area at intervals of, for example, d=about 20 squares. The length of the feeder filament 11 is approximately 600 fins.

Generally, the characteristic impedance of an aerial feeder line without a ground conductor nearby is several hundred ohms, which does not match the characteristic impedance (50 ohms) of the coaxial feeder line connected to terminal 15, so a considerable attenuation of the received power will occur. Conceivable. However, research by the inventors has revealed that by adjusting the wire width e of the feeder wire 11, it is possible to adjust the characteristic impedance even if the feeder wire is placed quite far from the window frame (ground conductor). It was done.

FIG. 3 is a graph of reception sensitivity (measured at a frequency of 80 MHz) when the width e of the feeder filament 11 is varied. As shown in this figure, it can be seen that by increasing the line width e to 31 or more, the receiving sensitivity is improved. This is thought to be because by making the wire 11 thicker, the capacitance relative to the vehicle body (ground conductor) increases, and the characteristic impedance is improved to approximately 50Ω even if the wire is not close to the window frame.

Note that the wire widths of the antenna element 11, the coupling wires 12, 14, etc. may be approximately 1 mm as in the conventional case. The strip-like feeder filament 13 is actually about 25 mm along the periphery of the window glass 1.
Since it is placed inside the ceramic-baked decorative masking 17 formed with a width of 3 mm or more, it will not be noticeable in appearance even if the line width is 3 mm or more. Furthermore, on the inside of the vehicle, the feeder line 13 is hidden by the pillar molding around the window glass and cannot be seen. During manufacturing, a ceramic material for masking 17 is printed and applied, and then heater wires 2, antenna elements 11, and feeder wires 1 made of conductive material such as grout paste are printed and applied.
3 etc. and then burnt the clay.

FIG. 4 shows a modified example, in which the antenna element 11 of FIG. 1 is separated into elements 11b and 11C in the middle, and the ends of each separated element are connected via two vertical coupling lines 12a and 12b. and is connected to the feeder filament 13. connecting line 12a,
12b has a spacing of about 5 mm, and antenna elements 11b and IIc
It has a function of impedance adjustment between the feeder wire 13 and the feeder wire 13. By dividing the antenna elements 11b and llc into two, they operate like a gouball 4, and have better matching with the impedance of the feeder wire 13 than the single wire element 11 in FIG.

FIG. 5 shows the reception sensitivity A in an example using the single wire antenna element 11 and one bonding wire 12 in FIG. It is a graph comparing the reception sensitivity B of the example using.

In the 70-90MHz FM broadcast band, characteristic B is better
It can be seen from this figure that the gain is increased compared to 1A.

FIG. 6 shows an example in which the power supply terminal 15 is linearly connected to one end of the feeder wire 13 without using the connection 'fIA14 of FIG. 1 or FIG. 4.

In the above embodiments, the single element antenna element 11 or ll
b. IIC is used, but it can also be applied to complex antenna patterns with bent elements or parallel elements.

Further, the antenna element 11 and the heater wire 2 may be combined.

〔Effect of the invention〕

As described above, the present invention provides a windowpane antenna in which a power supply terminal of the antenna is provided at a corner of a window glass of an automobile, in which a thick strip of line width is provided between the antenna element on the glass surface and the power supply terminal along the edge of the glass. Since the feeder wires are connected by conductive feeder wires, even if the feeder wires are placed sufficiently apart from the glass edge, it is possible to give the feeder wires a characteristic impedance matching that of the feeder cable. Therefore, even if the feeder line is drawn avoiding the adhesive or weather strip part that is interposed between the edge of the window glass and the automobile window frame, it will function as a low-loss feeder line and the reception sensitivity will be significantly reduced. do not. Therefore, there is no possibility of disconnection due to corrosion or electrolytic corrosion caused by moisture or adhesives that seep into the weather strip, and a high-gain receiving antenna that operates stably over a long period of time can be obtained.

According to the second aspect of the invention, since two parallel wires are used for the connection between the feeder wire and the antenna element, the receiving gain is improved by matching coupling between the antenna element and the feeder wire.

[Brief explanation of the drawing]

Figure 1 is a diagram of the conductor pattern of the rear window glass of an automobile to which the present invention is applied, Figure 2 is a detailed diagram of the feeder line, and Figure 3 is the FM reception sensitivity when changing the line [1] of the feeder line. , FIG. 4 is a window glass conductor pattern diagram showing another aspect of the coupling line between the feeder line and the antenna element, and FIG. 5 is the receiving sensitivity of the window glass antenna in FIGS. 1 and 4. FIG. 6 is a conductor pattern diagram showing a modification of the power supply terminal. In addition, in the symbols used in the drawings, they are 2----・11・・・・・・・12a, 12b 13−・16−・・・・・・・. Rear window glass heater wire...Antenna element coupling wire Feeder wire--Feeding terminal adhesive masking Rijin Tsuchiya Masaru Feeder" 10. B: i40 Sotosokuji, h, example Fig. 4 Hanawa J part/11 arrangement Fig. 6

Claims (1)

[Scope of Claims] 1. An antenna element conductor formed on a window glass surface, and a feeder wire for guiding a received signal of the antenna element conductor to a power feeding terminal in a glass corner portion, the feeder wire The line width along the edge of the window glass is 3m.
An automobile window glass antenna characterized by having a strip conductor of m or more. 2. The automobile window glass antenna according to claim 1, further comprising two closely parallel coupling lines between the current collection point of the antenna element and the feeder line.