WO2013038784A1

WO2013038784A1 - Glass antenna system

Info

Publication number: WO2013038784A1
Application number: PCT/JP2012/067183
Authority: WO
Inventors: 英明大島; 浩輔田中
Original assignee: 日本板硝子株式会社
Priority date: 2011-09-16
Filing date: 2012-07-05
Publication date: 2013-03-21
Also published as: JPWO2013038784A1

Abstract

A glass antenna system (10) is provided with the following: an antenna pattern (11) that has a pair of power supply units (110) printed on a glass surface (1); an amp module (12) that amplifies a signal received by the antenna pattern and is placed on the glass surface (1); and transmission lines (13) comprising two linear conductors that are printed on the glass surface, have a width (d) and spacing (D) necessary to match the characteristic impedance of the antenna pattern (11), connect the antenna pattern (11) and the amp module (12), and are disposed such that at least a portion of the lines are parallel.

Description

Glass antenna system

The present invention particularly relates to a glass antenna system suitable for mounting on a window glass of a vehicle as an antenna for a terrestrial digital television (hereinafter simply referred to as DTV: Digital Television).

For example, as shown in FIG. 7, in a DTV antenna in which an amplifier is installed on a glass surface, an amplifier module 200 is mounted on a pair of power supply portions (power supply terminals 101) of an antenna pattern 100. Unlike FM (Frequency Modulation) radio and analog TV antennas, DTV antennas are UHF (Ultra High Frequency) band signal waves, and are therefore often used for connection between the antenna and the amplifier module 200. When a wire (single wire) is used, the antenna performance becomes unstable due to the routing. For this reason, the performance is stabilized by installing the amplifier module 200 in the vicinity of the antenna on the glass surface and directly connecting to the antenna pattern 100.

Conventionally, it is suitable for radio reception of ultra-short waves, and in order to enable reception of TV broadcast waves, it is connected to a first element in which a horizontal line is connected to the tip of the vertical line and a tip of the vertical line. The second horizontal line and another horizontal line are arranged close to each other so as to sandwich the horizontal line of the first element, and the two horizontal lines are connected so as to wrap the end of the first element. A glass antenna for a vehicle having at least the above element is known (for example, see Patent Document 1).

In order to make it difficult to change the impedance depending on the installation location of the feed point, the ground conductor extends from the end of the connection conductor on the antenna conductor side toward the feed point and extends around the feed point to the end. There is also known an automotive glass antenna in which the distance d between the connection conductor and the ground conductor and the conductor width w1 of the connection conductor satisfy the relationship of 0.3 ≦ w1 / (w1 + 2d) ≦ 0.95. (For example, refer to Patent Document 2).

JP-A-6-314921 JP 2001-156520 A

According to the DTV antenna in which the amplifier is installed on the glass surface as described above, the amplifier module is installed on the glass surface, which has an aesthetic problem, and an amplifier concealment cover may be necessary. It becomes a factor of up. In addition, since the amplifier module is installed in the immediate vicinity of the antenna, the antenna can be placed only where the amplifier module can be installed, and as a result, the layout that prioritizes the antenna performance cannot be performed, and it may be difficult to ensure the performance. is there. Even if the amplifier module is moved to the pillar, a coaxial line is required to connect the amplifier module and the antenna. In this case, depending on the layout position of the amplifier module, the length of the coaxial line for connection changes, and the antenna performance May become unstable. In addition, depending on the state of the coaxial line, the antenna performance varies from vehicle type to vehicle type and may become unstable.

On the other hand, according to the glass antenna for a vehicle described in Patent Document 1, the antenna pattern itself is restricted because the setting of the antenna shape including the horizontal parallel two lines is limited in order to ensure the predetermined antenna characteristics. The degree of design freedom is small. In addition, according to the glass antenna for a vehicle described in Patent Document 2, since the ground conductor covers the periphery of the connection conductor connected to the antenna at a predetermined interval, the print area of the connection conductor is increased, and the aesthetic appearance is increased. Problems occur.

Further, according to the glass antenna for a vehicle described in Patent Document 2, it is a kind of unbalanced line because the ground conductor covers the periphery of the connection conductor, which is like a balanced antenna that does not use the vehicle body as a ground. If this technique is applied to a simple glass antenna, a problem of discontinuity of the reference potential occurs at the connection portion between the line and the antenna, and as a result, the antenna characteristics become unstable.

An object of the present invention is to provide a glass antenna system in which an antenna pattern can be arranged at a position where the antenna performance can be ensured to the maximum without depending on the arrangement position of the amplifier module.

According to the first aspect of the present invention, there is provided a glass antenna system in which an antenna is formed on a glass surface, the antenna element comprising an antenna pattern having a pair of feeding parts printed on the glass surface; An amplifier module installed on the glass surface for amplifying a signal received by the antenna element, and a line width and a distance necessary for matching with the characteristic impedance of the antenna pattern printed on the glass surface A glass antenna comprising: a transmission line composed of two linear conductors, at least a part of which is arranged in parallel, connecting the antenna pattern having the power supply unit and the amplifier module. A system is provided.

In the invention according to claim 2, preferably, the characteristic impedance Z ₀ of the transmission line is approximated by Z ₀ = A × log (2D / d) + B (where A and B are constants, d is a line width [ mm] and D are spaced [mm]).

In the invention according to claim 3, the constant A is preferably in the range of 115 at the minimum and 160 at the maximum.

In the invention according to claim 4, preferably, the constant B is in the range of 20 at the minimum and 30 at the maximum.

In the invention according to claim 5, preferably, the characteristic impedance of the transmission line is adjustable in a range of 75 [Ω] to 200 [Ω].

According to the present invention, a line feed and a set of two points having a line width and a spacing necessary for matching with a characteristic impedance of an antenna pattern printed on a glass surface and having a pair of feeds. By using a transmission line consisting of two linear conductors, at least part of which is arranged in parallel, connecting the antenna pattern having the antenna module and the amplifier module, the amplifier module can be separated from the antenna pattern having a pair of feeding parts. It can be laid out on the glass surface in an independent manner. Therefore, an antenna pattern having a pair of two-point power feeding units can be designed independently without depending on the layout position of the amplifier module, and the degree of design freedom is increased. As a result, the antenna pattern can be laid out at a position convenient for securing the antenna performance, and the antenna performance can be improved. Furthermore, the transmission line is stably connected to the glass surface because the amplifier module and the antenna pattern having a pair of feeding parts are connected via two linear conductors printed on the glass surface. Therefore, the electrical characteristics of the transmission line can be stably secured, and the antenna performance is stabilized.

Furthermore, by making the characteristic impedance of the transmission line adjustable within the range of 75 [Ω] to 200 [Ω], for example, the line width of the transmission line pattern is reduced and the line spacing is also manufactured. By adjusting to a problem-free level, a special manufacturing process is not required, and thus both electrical characteristics and manufacturing cost can be achieved.

It is the figure which showed the example which attached the glass antenna system by the Example of this invention to the rear window of the vehicle. It is the figure which expanded the glass antenna system shown in FIG. It is the figure which showed the evaluation conditions of the glass antenna system of the present Example shown in FIG. 2 with the comparative example. It is the figure which showed the frequency characteristic of the glass antenna system shown in FIG. 3 in contrast with the comparative example. It is the figure which showed the mounting position of the amplifier module used with the glass antenna system by a present Example with the comparative example. It is the figure which showed the performance contrast at the time of setting the mounting position of the amplifier module shown in FIG. 5 to the glass side. It is the figure which showed the arrangement | positioning form of the amplifier module in the conventional glass antenna system.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

(Configuration of Example)
As shown in FIG. 1, the glass antenna system according to the present embodiment is attached to a rear window of a vehicle, for example. According to the glass antenna system of the present embodiment, each antenna pattern for the DTV antenna 10, the AM radio antenna 20, and the FM radio antenna 30 is mounted in an empty area on the glass surface 1 of the rear window where the defogger 40 is mounted. ing. Hereinafter, the DTV antenna 10 will be exemplified and described in detail as a glass antenna system according to the present embodiment.

As shown in FIG. 2, the DTV antenna 10 includes an amplifier module 12 installed on the glass surface 1 (FIG. 1) that amplifies a signal received by the antenna element, and a pair of two-point feeding unit 110 as the antenna element. And an antenna pattern 11 having a transmission line 13. In the transmission line 13, two linear conductors are formed on the glass surface 1 as a printed pattern. The glass antenna system (DTV antenna 10) has a structure in which the amplifier module 12 and the antenna pattern 11 are connected by a transmission line 13.

The transmission line 13 is composed of two parallel linear conductors, and has a line width d of 10 mm to 0.5 mm and a line interval D (from the center line of the line width of one linear conductor to the other linear conductor. The distance between the center lines of the line width is 3.0 to 0.5 mm. In other words, the amplifier pattern 12 is not directly connected to the antenna pattern 11, but the antenna pattern 11 and the amplifier module 12 are connected via the transmission line 13.

(Effect of embodiment)
Since the transmission line 13 is formed on the glass surface 1 stably by forming the transmission line 13 composed of two parallel linear conductors in this way, the electrical characteristics of the transmission line 13 are improved. It can be secured stably, and this stabilizes the antenna performance. Moreover, since the antenna pattern 11 can be designed in a state independent of the amplifier module 12, the antenna pattern 11 should be arranged independently at a position where the antenna performance can be ensured to the maximum even if the feeding position is limited due to the vehicle type. Can do. Therefore, the antenna performance is improved. Furthermore, because the transmission line 13 is formed on the glass surface 1, the size of the glass so as not to cause a problem in manufacturing and aesthetics due to the characteristics of glass as a dielectric having a relatively large relative dielectric constant, It can suppress that the impedance of a transmission line becomes higher than necessary. The transmission line impedance can be adjusted in the range of 75 to 200 [Ω].

From the viewpoint of manufacturing and aesthetics, the line width d of the print pattern of the transmission line 13 is preferably 1 to 5 [mm]. On the other hand, in the design of the amplifier module 12, the characteristic impedance of the input part of the amplifier module 12 is desirably 150 [Ω] or less. Therefore, the line impedance of the printed pattern of the transmission line 13 is preferably 150 [Ω] or less. In this case, by setting the line width d to 1 to 5 [mm] and the line interval D to 0.5 to 3 [mm], the line impedance can be made 150 [Ω] or less, It is possible to form a transmission line with no problem from the point of view of beauty.

The meaning of setting the transmission line impedance in the range of 75 to 200 [Ω] is as follows. In other words, when designing a glass antenna that can ensure broadband characteristics, the characteristic impedance of the antenna is higher than a general value (50 [Ω] to 75 [Ω]) of 75 to 300 [Ω]. Here, when a glass antenna formed in a vehicle is considered, the amplifier module 12 is disposed in the vicinity of the antenna in order to ensure stable reception signal quality. The characteristic impedance of the input portion of the amplifier module 12 is noise resistance. 200 [Ω] or less is appropriate from the viewpoint of securing the value, and it is not preferable to set the value larger than necessary. Therefore, the characteristic impedance of the transmission line 13 for connecting the antenna pattern 11 and the amplifier module 12 needs to be adjustable in the range of 75 to 200 [Ω].

The characteristic impedance Z ₀ of the transmission line 13 formed on the glass surface 1 can be approximated by the following arithmetic expression (1). However, A and B are constants, d is a line width [mm], and D is an interval [mm].

Here, the range that the constants A and B can take will be described. In general, the characteristic impedance Z ₀ of the parallel two lines can be obtained by the following equation (2).

As is clear from the equation (2), the part corresponding to the constant A in the equation (1) is proportional to “1 / √ (εs)”. This “1 / √ (εs)” corresponds to the wavelength shortening rate of the radio wave in the dielectric having the relative dielectric constant εs. Therefore, it is considered that the constant A in the calculation formula (1) is also proportional to the wavelength shortening rate of the radio wave on the glass surface.

Incidentally, it is known that the wavelength shortening rate on the glass surface is related to the thickness of the glass used and the relative dielectric constant of the glass. Tempered glass and laminated glass are used as glass for vehicles, but the glass surface wavelength shortening rate is also limited to a predetermined range due to the limited range of relative permittivity and thickness when these glasses are used. . When a range that can be taken by the constant A of the arithmetic expression (1) is obtained from this limited range, 115 ≦ A ≦ 160.

Next, the constant B will be described. The arithmetic expressions (1) and (2) are different in whether or not the constant B exists. When this constant B was actually evaluated by a plurality of samplings including tempered glass and laminated glass, the results shown in Table 1 below were obtained.

According to Table 1, the constant B of the four samples can vary from 24 to 28. In addition, as a result of evaluating a plurality of other samples not shown in Table 1, it was found that the constant B was sufficient if it was in the range of 20 ≦ B ≦ 30.

According to the evaluation of the inventors, it was found that when a tempered glass having a thickness of 3.1 mm is used, an optimum characteristic impedance can be obtained by setting the constant A to “130” and the constant B to “27”. Further, it was found that when a laminated glass having a thickness of 4.7 mm is used, an optimum characteristic impedance can be obtained by setting the constant A to “129” and the constant B to “25”. It can be seen that the 3.1 mm thick tempered glass and the 4.7 mm thick laminated glass can ensure the characteristic impedance of almost the same level with the same shape. This means that patterns can be shared.

(Performance evaluation of embodiment)
FIGS. 3A and 3B are diagrams showing the evaluation conditions of the present example having the transmission line 13 and the comparative example not having the transmission line 13 when the layout position of the antenna pattern 11 is made common. is there. FIG. 3A shows the evaluation conditions of the present example having the transmission line 13 having a total length of 130 mm, and the characteristic evaluation point EP was used as the transmission line terminal. FIG. 3B shows the evaluation conditions of the comparative example that does not have the transmission line 13, and the characteristic evaluation point EP is set directly below the pair of power feeding parts. FIG. 4 shows the results of evaluation according to the evaluation conditions in comparison with the frequency characteristics of the present example and the comparative example.

As shown in FIG. 4, the average gain [dB] on the vertical axis is normalized so that the average value in the entire band (470 to 720 MHz) of the reference comparative example is 0 [dB]. In this example, within the terrestrial digital broadcast band of 470 to 720 [MHz], in the embodiment, the maximum value is 0.8 [dB] and the minimum value is −1.1 [dB] (the average in the band is −0. In the comparative example, the maximum value is 1.2 [dB] and the minimum value is −1.5 [dB] (in-band average is 0.0 [dB]). That is, even if the transmission line 13 is added, there is almost no difference in the average value, the maximum value, and the minimum value in the band, and even if the transmission line 13 is added as shown in this embodiment, the influence on the antenna performance is observed. I can't. This means that equivalent performance can be secured even if the mounting position of the amplifier module 12 is changed. Therefore, by using the transmission line 13 composed of two parallel linear patterns, the amplifier module 12 The degree of freedom of the mounting position can be ensured.

FIGS. 5A and 5B show the evaluation conditions of the present embodiment having the transmission line 13 and the comparative example not having the transmission line 13 when the mounting position of the amplifier module 12 is made common. FIG. 5A shows the present embodiment in which the amplifier module is mounted on the side of the glass, for example, and has a transmission line 13 that feeds the upper side when viewed from the antenna pattern 11. FIG. These are the comparative examples which do not have the transmission line 13 used as side feeding even if it sees from an unten pattern. Note that antenna patterns of other media are arranged in the vicinity in both the present example and the comparative example. FIG. 6 shows the frequency characteristics of the present embodiment and the comparative example in comparison.

In FIG. 6, as in FIG. 4, the average gain [dB] on the vertical axis is normalized so that the average value in the entire band (470 to 720 MHz) of the reference comparative example is 0 [dB]. Yes. According to FIG. 6, within the same band, in the embodiment, the maximum value is 3.1 [dB], the minimum value is −0.9 [dB] (in-band average is 0.4 [dB]), and the comparison is made. In the example, the maximum value is 1.9 [dB] and the minimum value is −2.4 [dB] (in-band average is 0.0 [dB]). This means that when the mounting position of the amplifier module 12 is, for example, the glass side, the antenna pattern 11 itself is laid out with priority on performance using the transmission line 13 composed of two parallel linear patterns. Means performance advantage.

(Effect of embodiment)
As described above, according to the glass antenna system according to the present embodiment, the antenna pattern 11 is connected by connecting the antenna pattern 11 having the pair of power feeding units 110 and the amplifier module 12 using the transmission line 13. The amplifier module 12 can be arranged on the glass surface 1 in an independent manner. As described above, the antenna pattern 11 can be designed without depending on the layout position of the amplifier module 12, and thus the degree of freedom in design is increased. Further, since the transmission line 13 is formed by two parallel linear conductors, it is not necessary to increase the area of the print pattern of the transmission line 13 more than necessary, and there is no fear of deteriorating the appearance. Furthermore, even if the transmission line 13 is directly connected to the antenna pattern 11 having a pair of two-point feeding units 110 that operate as a balanced or nearly balanced antenna, the transmission line 13 itself is also balanced, so that the antenna characteristics Does not become unstable.

Further, since the amplifier module 12 can be arranged independently of the antenna pattern 11, a dedicated concealment cover is not required, and the amplifier module 12 can be installed, for example, on a glass corner or a pillar cover. The pattern 11 itself can be set at an arbitrary position where performance can be easily secured. Therefore, even if there is a restriction on the layout position of the amplifier module 12, the antenna pattern 11 can be laid out at a position convenient for securing the antenna performance, and improvement of the antenna performance can be expected. That is, it is possible to avoid unnecessary antenna performance degradation due to different layouts for each vehicle type.

Further, since a printed pattern printed on the glass surface 1 is used as the transmission line 13 that connects the amplifier module 12 and the antenna pattern 11, the transmission line 13 is stably formed on the glass surface 1, and thus the transmission line Since the electrical characteristics of 13 can be stably secured, the antenna performance is also stabilized. In addition, by narrowing the line width of the printed pattern of the transmission line 13 and setting the line spacing to a level that does not cause a problem in manufacturing, a special manufacturing process is not required and the manufacturing cost does not increase. Further, by suppressing the characteristic impedance to 150 [Ω] or less, it is not necessary to unnecessarily increase the characteristic impedance of the input section of the amplifier module 12 to be used, and a special amplifier module 12 design is not required.

In addition, in order to cope with the manufacturing process (printing) with the prior art, the line interval needs to be 0.5 [mm] or more, but the characteristic impedance increases as the line interval increases. On the other hand, to reduce the characteristic impedance, it is possible to increase the line width. However, in order to reduce the impedance with the line width interval set larger than necessary, the line width is increased more than necessary. This causes a problem in aesthetics or glass modeling. Therefore, by setting the characteristic impedance to 70 [Ω] to 150 [Ω], both electrical characteristics and manufacturing cost can be achieved.

Moreover, according to the glass antenna system which concerns on a present Example, the two linear conductors used for the transmission line 13 shall be parallel in all the parts from the anten pattern 11 to the amplifier module 12. As described above, depending on the structure of the input section of the amplifier module 12, a two-line pattern that is partially parallel may be used.

The present invention is suitable for use in a DTV antenna system for receiving a terrestrial digital broadcast band 470-720 [MHz] mounted on a window glass of a vehicle.

DESCRIPTION OF SYMBOLS 1 ... Glass surface, 10 ... Glass antenna system (DTV antenna), 11 ... Antenna pattern, 12 ... Amplifier module, 13 ... Transmission line, 110 ... Feeding part.

Claims

A glass antenna system in which an antenna is formed on a glass surface,
An antenna element composed of an antenna pattern having a pair of feeding parts printed on the glass surface;
An amplifier module installed on the glass surface for amplifying a signal received by the antenna element;
The antenna pattern and the amplifier module printed on the glass surface, having a line width and a space necessary for matching with the characteristic impedance of the antenna pattern, and having the two-point set of the feeding portion. A transmission line consisting of two linear conductors connected at least partially in parallel;
A glass antenna system comprising:
The characteristic impedance Z 0 of the transmission line is approximated by Z 0 = A × log (2D / d) + B (where A and B are constants, d is a line width [mm], and D is an interval [mm]). The glass antenna system according to claim 1.
The glass antenna system according to claim 2, wherein the constant A is in a range of 115 at a minimum and 160 in a maximum.
3. The glass anten system according to claim 2, wherein the constant B is in a range of at least 20 and at most 30.
The glass antenna system according to any one of claims 1 to 4, wherein a characteristic impedance of the transmission line is adjustable in a range of 75 [Ω] to 200 [Ω].