JP2003163524A - Film antenna device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film antenna device which has a simple grounding and an excellent receiving sensitivity. <P>SOLUTION: The film antenna device which is stuck on a windshield glass includes a first film antenna 11, a second film antenna 12, and a third film antenna 13. The first film antenna 11 and the second film antenna 12 are installed on the same film, and have an antenna pattern portion capacitive- coupled to each other. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film antenna device retrofitted to a window glass of an automobile, and more particularly to a film antenna device for TV reception.

[0002]

2. Description of the Related Art In recent years, an example of mounting a TV device on an automobile has been increasing. In the case of a retrofit TV device, the antenna will also be attached later. Therefore, a film antenna that can be attached to a window glass of an automobile is often used.

This film antenna is constructed by forming an antenna pattern and a lead wire of this antenna element on a plastic film. The antenna pattern may be formed not only on one film but also on a film having a laminated structure.

In such a film antenna device, the film antenna can be easily attached to the windshield glass with a double-sided adhesive tape or the like.

Since such a film antenna has a limited mounting range due to the field of view of the windshield glass, it may not be possible to obtain sufficient reception sensitivity. Although the field of view regulation has been relaxed, the receiving sensitivity may still be insufficient.

By the way, in the glass antenna formed directly on the surface of the window glass, since the antenna pattern is adjusted in consideration of the influence of the body, it is possible to obtain good reception sensitivity. However, the film antenna to be attached later cannot be adjusted in consideration of the influence of the body to which it is attached, so that it may not be possible to obtain sufficient reception sensitivity.

[0007] Regarding the pasted antenna, the line width and the number of antenna patterns are regulated by the safety standards for road transportation vehicles (Article 29, paragraph 4, item 7). December 2, 1999
According to the Gazette of the 7th, No. 2778, and the Ministry of Transport Notification No. 820, the view restrictions in the above security standards are relaxed.

According to the security standard before being relaxed, the number of overlapping antenna patterns in the pasted antenna was limited to one in order to secure the visibility. Further, for example, in the windshield, the position where the pasted antenna is provided must be within 100 mm from the boundary line of the visible region opening of the windshield.

Regarding such a film antenna,
JP-A-9-130124, JP-A-2000-13122
And Japanese Patent Laid-Open No. 2001-77922.

By the way, a coaxial cable is generally used for a signal line of such a film antenna device, and a core wire is connected to a feeding portion of the lead wire, and a braided wire is connected to a vehicle body to obtain ground. I am trying.

In order to connect the ground, it was first necessary to largely remove the interior material around the windshield of the automobile. Then, the ground was screwed to the body or the rubber magnet ground plate 701 was attached to the vehicle body (see FIG. 15). Therefore, a lot of man-hours are required to connect the ground. In such a film antenna device, sufficient sensitivity is often not obtained without grounding.

[0012] Therefore, the applicant of the present invention has filed Japanese Patent Application Laid-Open No. 7-12291
No. 9 proposes a ground structure for a film antenna. Further, JP-A-9-130124 and JP-A-9-3
No. 07334 also proposes a ground structure for an antenna.

[0013]

[Patent Document 1] JP-A-7-122919

[Patent Document 2] Japanese Patent Laid-Open No. 9-130124

[Patent Document 3] Japanese Patent Laid-Open No. 9-307334

[Patent Document 4] Japanese Patent Laid-Open No. 2000-13122

[Patent Document 5] Japanese Unexamined Patent Application Publication No. 2001-77922

[Patent Document 6] JP 2001-274611 A

[Non-patent document 1] Safety standards for road vehicles (Ministry of Transport Ordinance No. 67 of 1947) Article 29, Paragraph 4, Item 7

[Non-Patent Document 2] Official Journal, December 27, 1999, No. 2778, Ministry of Transport Notification No. 820

[Non-Patent Document 3] Published by Japan Society of Automotive Engineers of Japan, Automotive Standard Safety Glass for Vehicles (M 501-94) Annex 1, Antenna for radio wave reception attached to front glass

[0014]

In such a film antenna, a sufficient receiving sensitivity is required even if it is applied to various body shapes.

Further, when the film antenna to be retrofitted is installed on the windshield glass, the installation space is limited. Furthermore, for TV broadcasting, VHF-L
Since there are three reception frequency bands of o, VHF-Hi, and UHF, three antenna patterns suitable for each reception band are required. Therefore, in the film antennas (211 and 213) shown in FIG. 15 described above, the film antenna is often attached around the inspection sticker 5 and the vehicle verification sticker 6 without a gap. In such a case, when the inspection sticker or the vehicle verification sticker is reattached at the time of vehicle inspection or regular inspection, it is necessary to remove the film antenna and attach it again.

Further, when the number of film antennas to be attached is large, there is a tendency that the work is inevitably complicated.

Incidentally, in the above-mentioned JP-A-7-122919,
Further improvements were required in the work of connecting the ground.

Therefore, an object of the present invention is to provide a film antenna device having excellent receiving sensitivity even when applied to various body shapes.

Another object of the present invention is to provide a simple ground structure in such a film antenna device.

Further, the present invention aims to improve the antenna performance of a film antenna attached to a windshield glass by relaxing the safety standard for road transport vehicles (Article 29, paragraph 4, item 7, visual field regulation). The purpose is to In addition, an object of the present invention is to provide a film antenna device capable of minimizing the obstruction of the visual field while improving the antenna performance.

According to the relaxed security standard (visual field regulation), the line width and the number of antennas to be attached are regulated depending on the place to be attached, but the attached antenna can be provided at any place on the windshield. became.
Although the safety standard is relaxed, it is preferable that there be no obstacles in front of the driver as much as possible in front of the driver.

[0022]

In order to solve the above problems, the present invention provides a film antenna device to be attached to a windshield glass as the invention of claim 1, wherein the film antenna device is a first film. An antenna, a second film antenna and a third film antenna, wherein the first film antenna and the second film antenna are provided on the same film, and are provided with antenna pattern portions capacitively coupled to each other. It is an antenna device.

According to a second aspect of the present invention, in the film antenna device according to the first aspect, the first film antenna and the second film antenna have counterclockwise and clockwise patterns, respectively, and constitute a diversity antenna. Film antenna device.

According to a third aspect of the present invention, in the film antenna apparatus according to the first aspect, each of the film antennas has a connector connected to a braided wire of a coaxial cable connected to each film antenna, and a pillar of a vehicle body. The film antenna device is grounded to the vehicle body by being attached to a conductive tape that is adhered to the part.

According to a fourth aspect of the present invention, in the film antenna apparatus according to the third aspect, the braided wires of the two coaxial cables connected to the first film antenna and the second film antenna are connected to one connector. Then, the film antenna device is grounded to the vehicle body by sticking this connector on the same conductive tape that is adhered to the pillar portion of the vehicle body.

According to a fifth aspect of the present invention, in the film antenna apparatus according to the first aspect, each of the film antennas has a lengthwise dimension exceeding at least 100 mm.

According to a sixth aspect of the present invention, in the film antenna device according to the first aspect, the mounting position of the lowermost antenna element of each film antenna is 120 m from the boundary line of the visible region opening above the windshield.
The film antenna device is within m.

According to a seventh aspect of the present invention, in the film antenna apparatus according to the sixth aspect, the mounting position of the lowermost antenna element of each of the film antennas is 110 m from the boundary line of the visible region opening above the windshield.
The film antenna device is within m.

According to an eighth aspect of the present invention, in the film antenna device according to the first aspect, the first film is
The film antenna device has an opening in its central portion.

According to a ninth aspect of the present invention, in the film antenna device according to the eighth aspect, the capacitively coupled antenna pattern portion is provided around the opening.

According to a tenth aspect of the present invention, in the film antenna device according to the first aspect, the first film antenna, the second film antenna and the third film antenna have a substantially rectangular shape. Is.

According to an eleventh aspect of the present invention, the film antenna device according to the first aspect is provided so as to avoid the vehicle verification seal or the inspection seal.

A feature of the present invention is that the first film antenna and the second film antenna are provided on the same film, and the antenna pattern portions that are capacitively coupled to each other are provided. Since the first film antenna and the second film antenna are capacitively coupled to each other, they have excellent reception performance in a wide band from VHF-Lo to VHF-Hi to UHF.

Further, it is preferable that the first film antenna and the second film antenna have counterclockwise and clockwise patterns, respectively, in order to form the capacitive coupling by arranging the patterns from the power supply terminal.

According to the relaxed security standard (visual field regulation), although the line width and the number of antennas to be attached are regulated depending on the place to be attached, the attached antenna can be provided at any place on the windshield. became.

Further, as described above, the security standard before being relaxed limits the number of overlapping antenna patterns of the pasted antennas to one, but this regulation has also been removed. Therefore, a film antenna in which two antenna patterns are formed on the same film base can be used.

In the film antenna device of the present invention,
Similar to Japanese Patent Laid-Open No. 7-122919 mentioned above, a capacitor is formed between the braided wire of the coaxial cable and the vehicle body and capacitively coupled to form a body ground. In this case, the frequency characteristics greatly differ depending on the type of insulator.
When the electrode conductors are opposed to each other with the insulator sandwiched in the / TV band (for example, 100 MHz), the impedance is 0.0015Ω if the capacitance is about 1 μF.

For example, it is assumed that the electrodes are opposed to a coated metal plate (vehicle body) with a coating film (insulator) sandwiched therebetween, as in the case of an automobile body. With such a configuration,
If the formed capacitance is about 1 μF, although a DC signal can be blocked, an AC signal can pass through, so that it can function as a ground capacitively coupled in high frequency.

Further, the impedance can be further reduced by narrowing the distance between the electrode facing the vehicle body and increasing the area of the electrode.

The film antenna device according to the present invention may be attached to the front upper part of the driver's seat and the passenger seat in the windshield. Particularly on the passenger side, a film antenna may be attached between the inspection sticker and the vehicle verification stick as shown in FIG. 1, and it is not necessary to attach the film antenna so as to surround the inspection sticker and the vehicle verification stick. Similarly, on the driver's side, the vehicle verification sticker may be avoided and it may be attached to the upper front of the driver's seat.

As described above, the film antenna according to the present invention can be attached without using the inspection sticker and the vehicle verification sticker. Therefore, it is not necessary to remove the film antenna when the inspection sticker or the vehicle verification sticker is replaced during vehicle inspection or regular inspection.

At this time, it is preferable that the first film antenna and the second film antenna are provided on the same film. If two antennas are formed on the same film,
Since the number of film antennas can be reduced, the attaching work can be reduced.

As described above, the film antenna apparatus according to the present invention can be attached to avoid the inspection sticker and the vehicle verification sticker. Therefore, it is not necessary to remove the film antenna when the inspection sticker or the vehicle verification sticker is replaced during vehicle inspection or regular inspection.

Further, it is preferable to make the film antenna device in which the dimension of each film antenna in the longitudinal direction exceeds at least 100 mm due to the relaxation of the visual field regulation. Further, it is preferable that the lowermost mounting position of the antenna element of each of the film antennas be within 120 mm from the boundary line of the visible region opening above the windshield. By setting in this way, the antenna performance can be ensured and the obstruction of the visual field can be minimized.

If the mounting position of the lowermost part of the antenna element is set within 120 mm from the boundary line of the opening of the visible region, it is less likely that the driver or other occupants will have an important visual field, and thus the obstruction of the visual field is minimized. It can be limited.

Further, if the mounting position is within 110 mm from the boundary line of the visible area opening, the obstruction of the visual field can be further reduced. In particular, this limitation is effective for the film antenna provided in front of the driver who needs to secure the visibility.

In this specification, the vertical dimension of the film antenna is defined as the distance between the antenna patterns on the upper side and the lower side. However, this is different from the longitudinal dimension of the base film.

The opaque portion above the windshield specifically means a ceramic printed portion. Further, when the inner peripheral portion of this ceramic print is formed in a dot pattern, the boundary line may be defined as the innermost peripheral edge of the dot pattern.

[0049]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below with reference to the drawings.

(Embodiment) FIG. 1 shows a schematic view of a state in which the film antenna device 1 according to the present invention is attached to a windshield 10 as viewed from inside the vehicle. Further, a plan view of the film antennas 11 and 12 is shown in FIG. 2, and a plan view of the film antenna 13 is shown in FIG.

In the film antenna device 1, the signal from each film antenna is input to the receiver 40 through the coaxial cable 8 and the selector section 30.
A monitor unit 50 is connected to the receiver 40. The braided wire 82 of the coaxial cable 8 is joined to the conductive tape 9 through the connector 7 and is connected to the body metal portion 20 of the body.
It is grounded to 2.

This film antenna (11, 12, 1
In 3), the antenna patterns (31, 32, 33) were printed with silver paste on the polyester film bases (21, 22). The film base is
For example, the thickness is 75 μm. Next, after drying the printed silver paste, a clear coating (for example, SG manufactured by Seiko Advance Co., Ltd .: SG
429B).

FIG. 2 shows patterns (3) of the first and second film antennas provided on the same film base 21.
1, 32) are shown. FIG. 3 shows the pattern (33) of the third film antenna. In addition to the antenna pattern, each film antenna has a feeding point (41, 4).
2, 43) are provided. The above-mentioned clear coating is not formed on this portion in order to maintain conductivity. The core of the coaxial cable is connected to this feeding point. In the area surrounded by each antenna pattern, the central portion (23) of the film base is cut out and removed. That is, the film base has an opening portion at its center.

In this film antenna device, the capacitively coupled antenna pattern portion is preferably provided around the opening. It is convenient to construct a diversity antenna when the first film antenna and the second film antenna have counterclockwise and clockwise patterns, respectively.

In this film antenna device, the first
The film antenna, the second film antenna, and the third film antenna preferably have a substantially rectangular shape. This is because the area occupied by the film antenna can be increased. In an actual film antenna, it is preferable that the film antenna is formed along the curve of the upper side of the windshield. It is not exactly rectangular in shape, but is substantially rectangular.

In FIGS. 2 and 3, each film antenna pattern is represented as a rectangle in order to simplify drawing. However, in this embodiment, strictly speaking, the upper and lower patterns of each film antenna are formed so as to follow the curve of the upper side of the windshield.

Each pattern of the first, second and third film antennas is not particularly limited, but it is necessary that the first and second film antennas are provided with antenna patterns which form capacitive coupling with each other. A modification of each pattern of the first and second film antennas is shown in FIG.

In the first and second film antennas, the frequency band that is preferable for capacitive coupling is VHF.
-Lo and VHF-Hi.

For example, in the VHF-Hi band, the length of the portion forming the capacitive coupling is at least 200 mm (= (1 / 4λ) × k) when λ = 225 MHz, and at least 270 mm when λ = 167 MHz. (=
It is necessary to set (1 / 4λ) × k). Also, V
In the HF-Lo band, the length of the part that forms capacitive coupling is 500 mm when λ = 90 MHz is a typical value.
(= (1 / 4λ) × k) is required.

Therefore, the length of the antenna pattern portion forming the capacitive coupling is preferably 200 to 500 mm. The upper limit of this length may be limited by the antenna pattern.

The distance between the antenna patterns is 5
mm or less is preferable. Note that these dimensions have a shortening rate k (≈0.
It is a value multiplied by 6).

The film antenna device 1 is attached to the front upper part of the driver's seat and the passenger seat of the windshield 10 when viewed from the inside of the vehicle (see FIG. 1). First, the first film antenna 11 and the second film antenna 12 are formed on the same first film base. An adhesive is applied to the back surface of the film base. The first film base is attached to the upper front part of the passenger seat. The sticking position is preferably between the car verification sticker and the inspection and maintenance sticker.

The third film antenna 13 is formed on the second film base. The second film base is attached to the front upper part of the driver's seat, avoiding the vehicle verification seal.

In any of the film antennas, the line width of the antenna pattern is preferably as thin as possible in appearance. Specifically, 0.3 mm or less is preferable. Figure 2,
In the example of FIG. 3, it is 0.2 mm.

By the way, the dimensions of the film antenna should be such that the required reception sensitivity and appearance do not hinder the appearance.
It must be decided in consideration. In order to increase the reception sensitivity, an antenna pattern as large as possible is preferable, but from the viewpoint of appearance, a pattern too large is not preferable. It should be noted that the relaxation of the field of view restrictions made it possible to increase the vertical dimension, so this dimension should be at least 100 mm, and the upper limit is 1 mm.
It was set to 20 mm.

In any of the above-described film antennas, if the upper part of the antenna pattern is hidden by the ceramic print, the line width of that part may be thick. However, if the upper side is not hidden by the ceramic print, the line width is preferably thin. In each of the film antennas shown in FIGS. 2, 3, and 4, the central portion of the wide pattern is removed from the upper side of the antenna pattern to form an elongated rectangle or a ladder (52, 53). There is.

In addition to the antenna pattern, each film antenna is provided with a portion serving as a feeding point. The above-mentioned clear coating is not formed on this portion in order to maintain conductivity. The core of the coaxial cable is connected to this feeding point.

As shown in FIG. 5, the core wire 81 of the coaxial cable 8 which is a signal wire is provided with a pair of connecting fittings (85, 8).
It is connected to the electric wire 83 via 6). Further, the electric wire 83 is connected to the connector 7. Connector 7
A metal foil 71 connected to the electric wire 83 is exposed on the back surface of the sheet (see FIG. 6). The back surface of the connector may be provided with a double-sided adhesive tape 72 or an adhesive may be applied.

The connector 7 is attached to the portion of the feeding point to connect the core wire 81 to the antenna pattern 3.

Next, the earth structure will be described with reference to FIGS. 1, 5 and 6. First, the conductive tape 9 having a conductive adhesive applied to the back surface thereof is attached to the vehicle body 200 having the coating film 201 formed thereon (see FIG. 6). As an example of the dimension, width 10 × length 150 mm can be shown. In addition, for example, it has been confirmed by an experiment that an effective ground can be obtained if the area is 10 mm wide × 100 mm long (1000 mm ² ).

In the above case, the coating film 201 serves as an insulating layer, and capacitive coupling is formed between the conductive adhesive and the vehicle body. Further, the coating film 201 is partially removed and, for example, a metal foil 91 to which a double-sided adhesive tape is attached is used as a conductive tape so that capacitive coupling is formed between the metal foil and the vehicle body metal portion 202. May be.

Specifically, the conductive tape 9 may be attached to the metal portion of the pillar of the vehicle body 200 covered with the interior material around the windshield 10. The pillar portion is preferable because the metal portion can be easily exposed by removing the resin cover which is the interior material, and thus the work is simple and preferable. In this embodiment, the conductive tape 9 is attached to each of the left and right pillar portions.

The first and second film antennas are
Since it is provided on the same film base 21, the first
Alternatively, the ground of the second film antenna may be shared (see FIG. 7), and the same conductive tape for forming the ground may be attached (see FIG. 1). In this case, the mounting work is simple and preferable.

Depending on the handling of the coaxial cable,
A conductive tape for forming a ground may be attached only to the pillar portion on one side. In this case, since only one resin cover needs to be removed, the work becomes easier.

Next, the braided wire 82 of the coaxial cable 8 which is a ground wire is connected to the electric wire 84 through a pair of connecting fittings (85, 86). Further, the electric wire 84
Are connected to the connector 7 (see FIG. 5).

By attaching the connector 7 to the conductive tape 9, the braided wire 82 of the coaxial cable can be connected to the conductive tape 9 (see FIG. 6). Then, the conductive tape 9 and the vehicle body metal portion 202 form a capacitor, so that it can be grounded. The braided wire and the conductive tape may be directly connected by soldering without using the connector.

The length of the braided wire of the coaxial cable is preferably as short as possible for the antenna performance within the range where workability is not impaired. In this embodiment, the third film antenna provided on the driver side has a thickness of 50 mm, and the first and second film antennas provided on the passenger side have a thickness of 100 mm.

Three film antennas (11, 1
Since it is necessary to separately connect the grounds to 2, 2 and 13), the above-mentioned three connectors are provided.

The core wire of the coaxial cable which is the signal wire will be described. The core wire that is not shielded by the braided wire,
Since the noise easily mixes in, it is preferable that the exposed core wire portion is as short as possible. Its length is up to 200 mm. From the viewpoint of installation work, at least 1
A length of about 00 mm is necessary. In this example, 1
It was set to 50 mm.

Further, a total of three coaxial cables 8 connected to the three film antennas are arranged around the windshield (see FIG. 1). The coaxial cable 8
It is connected to the selector unit 30. This selector can control signals from the receiver to select the signals from the above three antennas according to the reception band. This selected signal is connected to the receiver 40 via one coaxial cable. An amplifier may be provided in the selector unit 30.

Further, the signal from the receiver 40 is connected to a monitor 50 such as a liquid crystal display device.

(Antenna Performance) The reception performance of the film antenna device of the above-mentioned embodiment was measured. The results are shown in Table 1.
And shown in FIG. For reference, Table 1 and FIG. 10 also show the reception performance of the film antenna device (see FIG. 9) in which the first antenna and the second antenna shown in FIG. 8 are not capacitively coupled. In any film antenna device, 3
It is the measurement data when a diversity antenna is configured by one film antenna.

In FIGS. 8 and 10, the line types are as follows. Solid line: first antenna, broken line: second antenna, one-dot chain line: third antenna, two-dot chain line: diversity

[0084]

[Table 1]

Further, in the embodiment, the antenna performance when the first antenna and the second antenna are capacitively coupled and when they are independent antennas are shown as VSWR (Voltag
e Standing Wave Ratio). The results are shown in FIGS. 11 to 14. Table 2 shows the VSWR values at typical frequencies for each antenna.

When the first antenna and the second antenna are capacitively coupled, there are two cases, that is, when the second antenna is capacitively coupled to the first antenna and when the first antenna is capacitively coupled to the second antenna. Has an antenna. That is, there are two antennas when viewed from the respective terminal sides. They are referred to as a first antenna (combined) and a second antenna (combined).

[0087]

[Table 2] ―――――――――――――――――――――――――――――――――――       Antenna VSWR value                               90 108 170 220 (MHz) ―――――――――――――――――――――――――――――――――――   1st antenna (single) 49.727 27.873 6.742 20.078   1st antenna (coupled) 21.473 3.199 2.076 17.256   Second antenna (single) 4.822 19.227 19.787 1.647   Second antenna (combined) 5.721 22.86 16.828 1.378 ―――――――――――――――――――――――――――――――――――

FIG. 11 shows the result of VSWR when the first antenna is used alone. The vertical axis represents VSWR, and the horizontal axis represents frequency. The smaller the value on the vertical axis, the better the antenna performance. As can be seen from FIG. 11, with the first antenna alone, effective antenna performance is obtained in the frequency range around 90 and 220 MHz.

FIG. 12 shows the case where the second antenna is capacitively coupled to the first antenna. It can be seen that, when capacitively coupled, the antenna performance is slightly improved in the frequency range around 90 and 220 MHz.

FIG. 13 shows the result of VSWR when the second antenna is used alone. As can be seen from FIG. 13, with the second antenna alone, effective antenna performance is obtained only in the frequency range around 170 MHz.

FIG. 14 shows a case where the first antenna is capacitively coupled to the second antenna. 108M when capacitively coupled
It can be seen that effective antenna performance is obtained even in the frequency range around Hz.

Further, from the results of FIGS. 12 and 14, the first
It can be seen that when the antenna and the second antenna are capacitively coupled, effective antenna performance is obtained at any of the typical frequencies of 90, 108, 170 and 220 MHz.

That is, when the first antenna and the second antenna are capacitively coupled to select an antenna having good performance,
It has been found that excellent antenna performance can be obtained in the VHF-Lo and VHF-Hi bands.

[0094]

As described above, according to the present invention, in the film antenna device, the first antenna and the second antenna are capacitively coupled. Therefore, it is possible to obtain excellent reception sensitivity.

Further, the ground of each film antenna is connected by forming a capacitor with the metal portion of the pillar portion of the vehicle body and the conductive adhesive tape. Therefore, the post-attached film antenna device can be easily attached.

Further, since it is sufficient to remove the resin cover of the pillar portion at the time of connecting the ground, there is an advantage that the working time can be shortened.

Further, the retrofitted film antenna device does not need to remove the film antenna when the inspection sticker or the vehicle verification sticker is replaced.

Further, since the two film antennas are formed on the same film base, the attaching work itself and the positioning work can be reduced.

[Brief description of drawings]

FIG. 1 is a plan view illustrating an attachment example of a film antenna device according to the present invention.

FIG. 2 is a plan view of first and second film antennas.

FIG. 3 is a plan view of a third film antenna.

FIG. 4 is a diagram showing a modified example of the first and second film antennas.

FIG. 5 is a schematic diagram illustrating a connection between a coaxial cable and a connector that connects a film antenna and a ground.

FIG. 6 is a diagram illustrating a structure of a connector used in the present invention and a ground structure.

FIG. 7 is a schematic diagram for explaining the connection of the connector when the ground is shared.

FIG. 8 is a graph of reception sensitivity in the example of the present invention.

FIG. 9 is a schematic diagram illustrating a film antenna device of a reference example.

FIG. 10 is a graph of reception sensitivity in the reference example.

FIG. 11 is a diagram showing a VSWR result of the first film antenna alone.

FIG. 12 is a diagram showing a result of VSWR when the second film antenna is capacitively coupled to the first film antenna.

FIG. 13 is a diagram showing a VSWR result of the second film antenna alone.

FIG. 14 is a diagram showing a VSWR result when the first film antenna is capacitively coupled to the second film antenna.

FIG. 15 is a diagram illustrating a retrofitted film antenna that is a conventional example.

[Explanation of symbols]

1: film antenna device 11: first film antenna 12: second film antenna 13: third film antenna 2: film (base) 21: first film base 22: second film base 23: notch 31 of film base: 1st antenna pattern 32: 2nd antenna pattern 33: 3rd antenna pattern 52, 53: elongated rectangular or ladder-shaped part 42 of antenna pattern 42: 2nd feeding point 43: 3rd feeding point 5: inspection and maintenance certificate seal 6: car Verification seal 7: Connector 71: Metal foil 72: Double-sided adhesive tape 8: Coaxial cable 81: Core wire 82: Braided wire 83, 84: Electric wire 85, 86: Connection fitting 9: Conductive tape 91: Metal foil 92: Double-sided adhesive Tape 10: Windshield glass 200: Car body (body) 201: Paint film 202: Car body metal part 30: Selector 40: receiver 50: monitor unit

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 3D020 BA13 BB01 BC10 BD05                 5J046 AA04 AA09 AA12 AB11 AB17                       LA01 LA05 LA13 LA15 LA19                       TA05 TA07 TA08                 5J047 AA04 AA09 AA12 AB11 AB17                       EC02

Claims (11)

[Claims] 1. A film antenna device attached to a windshield glass, wherein the film antenna device is a first film antenna,
A film antenna device comprising a second film antenna and a third film antenna, wherein the first film antenna and the second film antenna are provided on the same film and have antenna pattern portions capacitively coupled to each other. . 2. The film antenna device according to claim 1, wherein the first film antenna and the second film antenna are
A film antenna device that forms a diversity antenna, with counterclockwise and clockwise patterns, respectively. 3. The film antenna device according to claim 1, wherein each film antenna has a connector connected to a braided wire of a coaxial cable connected to each film antenna, which is adhered to a pillar portion of a vehicle body. A film antenna device that is grounded to the vehicle body by pasting it on a conductive tape. 4. The film antenna device according to claim 3, wherein the braided wires of the two coaxial cables connected to the first film antenna and the second film antenna are connected to one connector, and the connector is connected. A film antenna device that is grounded to the vehicle body by sticking it on the same conductive tape that is adhered to the pillars of the vehicle body. 5. The film antenna device according to claim 1, wherein each film antenna has a longitudinal dimension of at least 1.
Film antenna device that exceeds 00 mm. 6. The film antenna device according to claim 1, wherein the mounting position of the lowermost part of the antenna element of each film antenna is within 120 mm from the boundary line of the visible region opening above the windshield. . 7. The film antenna device according to claim 6, wherein the mounting position of the lowermost part of the antenna element of each film antenna is within 110 mm from the boundary line of the visible region opening above the windshield. . 8. The film antenna device according to claim 1, wherein the first film has an opening in a central portion thereof. 9. The film antenna device according to claim 8, wherein the capacitively coupled antenna pattern portion is provided around the opening. 10. The film antenna device according to claim 1, wherein the first film antenna, the second film antenna, and the third film antenna are substantially rectangular in shape. 11. The film antenna device according to claim 1, wherein the film antenna device is provided so as to avoid a vehicle verification sticker or an inspection sticker.