JPH11145717A - Glass antenna for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure sufficient reception sensitivity and view by providing a part of or the entire plural non-feeding conductors which are not connected to a feeding point between an antenna conductor and a vehicle opening part and specifying the conductor width of the non-feeding conductor. SOLUTION: The conductor width of plural non-feeding conductors 4a and 4b provided between an antenna conductor 2 connected with a feeding point 6 in a loop form or a semi-loop form, and the vehicle opening part 7 is set in a range of 0.1-0.8 mm. When conductor width is not more than 0.8 mm, satisfactory view can be secured compared to a case that it exceeds 0.8 mm. The pattern forms of the non-feeding conductors 4a and 4b are not especially limited, but an interval L is preferable that they be in a range of 0.5-10 mm from the viewpoint of sensitivity improvement. The shortest distance between the non-feeding conductors 4a and 4b and the vehicle opening part 7 is normally not more than 50 mm. The conductor lengths of the antenna conductor 2, an auxiliary antenna conductor 3 and the non-feeding conductors 4a and 4b are desirable to be in the range of (λ/4)×K-2λ×K, wherein the λ is the wavelength of a desired reception frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to FM broadcasting, television V
The present invention relates to a glass antenna for a vehicle which is suitable for receiving a high frequency band such as an HF band, and particularly suitable for being provided on a side window glass plate of an automobile.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 3, an antenna conductor 32, an auxiliary antenna conductor 33 and a feed point 36 are provided on a side window glass plate 1 at the rear of an automobile, and these are used as antennas to provide FM broadcasting and television. We were receiving broadcasts.

In FIG. 3, reference numeral 8 denotes a lead wire, 9 denotes a preamplifier, and 10 denotes a coaxial cable. The length of the periphery of the vehicle body opening (almost the same as the outer circumference of the window glass plate fitted into the vehicle body opening) is 2500 mm, the conductor length of the antenna conductor 32 is 1000 mm, and the conductor length of the auxiliary antenna conductor 33 is 1
500 mm, antenna conductor 32 and auxiliary antenna conductor 33
Is 20 mm, and the shortest distance between the antenna conductor 32 and the vehicle body opening is 70 mm.

A conventional example different from that shown in FIG. 3 is proposed in Japanese Utility Model Laid-Open No. 4-78809 (FIG. 9). In FIG. 9, 2 is an antenna conductor, 4 is a non-feeding conductor, 6 is a feeding point, and 7 is a vehicle body opening.

[0005]

The conventional glass antenna shown in FIG. 3 has a problem in that the receiving sensitivity is insufficient in the FM broadcasting band (76 to 90 MHz), and the broadcast cannot be received well in an area where radio waves are weak. .

FIG. 4 shows a frequency characteristic of the receiving sensitivity of the conventional example shown in FIG. Although the dimensions of the antenna conductor 32 and the auxiliary antenna conductor 33 are adjusted to increase the reception sensitivity in the FM broadcasting band, as shown in FIG. 4, there is a high reception sensitivity range near 120 MHz which is higher than 110 MHz. On the other hand, the reception sensitivity is low in the FM broadcast band. In addition,
The resonance frequency of the vehicle body opening used in the conventional example of FIG. 3 was 120 MHz when measured.

[0007] The reason why the range of high receiving sensitivity is formed at a frequency higher than 110 MHz (around 120 MHz in the example of FIG. 3) is usually that the antenna conductor 32 or the auxiliary antenna conductor 3
3 and the window frame (vehicle body opening) of the window glass plate are closely coupled to each other, so that the body opening also functions as an antenna in a high frequency band such as the FM broadcast band.

[0008] When the vehicle body opening of the window such as a side window glass plate is small, it resonates with the vehicle body opening in a frequency range higher than that of the FM broadcasting band and easily tunes, and a frequency region other than the tuning frequency band (in this case, FM broadcasting (Out-of-band) reception sensitivity. That is, the size of the window body opening has a frequency tuning dependency, and the size of the window body opening affects the reception characteristics of the antenna conductor.

Further, when the vehicle body opening resonates in a desired reception frequency band, there is a problem that flatness of reception sensitivity cannot be ensured in the reception frequency band. Also, for example,
In an RV car or the like, since the rear window glass plate is narrow and the area where the antenna conductor can be provided on the rear window glass plate is small, sufficient reception characteristics cannot be obtained.

Although the conventional glass antenna shown in FIG. 9 can contribute to the improvement of the sensitivity of the FM broadcast band, the conventional glass antenna
The conductor width of the parasitic conductor 4 which is preferable for improving the sensitivity of the broadcasting band is 1
mm and the conductor width of the parasitic conductor 4 is 1
mm or more, there is a disadvantage that the securing of the field of view is hindered,
In particular, when the opening of the vehicle body is small, the problem becomes remarkable.

Therefore, development of a glass antenna which can be provided in a small space and has a sufficient receiving sensitivity and a sufficient field of view has been desired.

[0012]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has a power supply point provided on a window glass plate of a vehicle, an antenna conductor connected to the power supply point, and
A plurality of parasitic conductors not connected to the feeding point,
Part or all of the parasitic conductor is provided between the antenna conductor and the vehicle body opening, the antenna conductor has a loop shape or a semi-loop shape, and the conductor width of the parasitic conductor is 0.1 to 0.
Provided is a glass antenna for a vehicle, which is 8 mm.

Further, the present invention provides the above-mentioned glass antenna for a vehicle, wherein the distance between the antenna conductor and the parasitic conductor is 10 mm or less. In addition, the present invention provides the glass antenna for a vehicle, wherein the plurality of parasitic conductors are connected to each other by a connection line. Further, the present invention provides the glass antenna for a vehicle, wherein the vehicle body opening resonates at a frequency higher than the lowest frequency of a desired reception frequency band.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 1 is a configuration diagram of a typical example of a glass antenna for a vehicle according to the present invention. In FIG. 1, 2 is an antenna conductor, 3 is an auxiliary antenna conductor, 4a and 4b are parasitic conductors, 5a and 5b are connection conductors, 6 is a feeding point, 7 is a vehicle body opening, L is an antenna conductor and a parasitic conductor 4a. And the interval.

In FIG. 1, the antenna conductor 2 has a semi-loop shape. However, the present invention is not limited to this, and the present invention can be applied to a loop-shaped pattern. The half-loop shape means that a part of the loop is broken, and a length of about １ ／ of the entire loop is also called a half-loop shape.

The antenna conductor 2 needs to be electrically connected to the feeding point. However, the antenna conductor 2 may be directly connected to the feeding point, or may be connected to the feeding point via a connecting conductor. It may be connected. In FIG. 1, the antenna conductor 2 is provided in a semi-loop shape substantially parallel to the vehicle body opening 7 into which the side window glass plate 1 is to be fitted. However, the antenna conductor 2 does not necessarily have to be provided substantially parallel to the vehicle body opening 7 of the side window glass plate 1.

In the present invention, a plurality of parasitic conductors are provided between the antenna conductor and the vehicle body opening, and the conductor width of the parasitic conductor is in the range of 0.1 to 0.8 mm. When the conductor width of the parasitic conductor is 0.8 mm or less, a better visual field can be secured as compared with the case where the conductor width is more than 0.8 mm. Also, the conductor width of the parasitic conductor is 0.1 mm or more is 0.1 mm
If it is less than the above, it is difficult to manufacture. A preferable range of the conductor width of the parasitic conductor is 0.1 to 0.6 mm, and a more preferable range is 0.1 to 0.4 mm. Similarly, the conductor width of the antenna conductor is set to 0.1 to 0.
A range of 8 mm is preferable, 0.1 to 0.6 mm is more preferable, and 0.1 to 0.4 mm is particularly preferable.

The electrical length of the parasitic conductor (the length corresponding to the propagation wavelength of radio waves in the air) is the value obtained by dividing the conductor length of the parasitic conductor by the glass shortening rate K, that is, the conductor length of the parasitic conductor / glass. Since the shortening rate is K and the apparent vehicle body opening is large, it is easy to tune to a lower frequency than the conventional vehicle body opening, and the receiving sensitivity of the FM broadcast band and the television VHF band is improved.
Sufficient reception characteristics can be obtained. The glass shortening rate K is
Usually, it is 0.64.

In FIG. 1, the parasitic conductors 4a and 4b are provided substantially in parallel with the antenna conductor 2 and the vehicle body opening 7 in a semi-loop shape. However, the parasitic conductors 4a and 4b may have one or a plurality of straight, curved or loop shapes, and need not necessarily be provided substantially parallel to the vehicle body opening 7 of the side window glass plate 1. Also, in FIG.
Although this is provided, the number is not limited to this and may be one or three or more.

That is, the pattern shape of the parasitic conductor is not particularly limited, and it can be used as long as a part or the whole of the parasitic conductor is provided between the antenna conductor and the vehicle body opening.
However, it is preferable that most of the parasitic conductor is provided between the antenna conductor and the vehicle body opening from the viewpoint of improving the receiving sensitivity. Therefore, if the antenna conductor 2 is a semi-loop or loop-shaped conductor pattern, it is preferable that the parasitic conductor also be a semi-loop or loop-shaped conductor pattern from the viewpoint of improving reception sensitivity.

FIG. 1 shows a parasitic conductor 4a and a parasitic conductor 4b.
Are connected by connecting conductors 5a and 5b. But,
The present invention is not limited to this, and the parasitic conductor 4a and the parasitic conductor 4b need not be connected. In short, when a plurality of parasitic conductors are provided, they can be used without connecting each parasitic conductor.

From the viewpoint of improving the sensitivity, the interval L is 0.5 to
A range of 10 mm is preferable, and a range of 0.5 to 6 mm is more preferable. When the interval L is 10 mm or less, 1
The sensitivity is generally improved by 0.5 dB or more as compared with the case where the length is more than 0 mm. When the distance L is 6 mm or less, 6 m
In general, the sensitivity is improved by 0.2 dB or more as compared with the case where m is more than m. If the interval L is less than 0.5 mm, it is difficult to manufacture,
Not preferred.

The auxiliary antenna conductor 3 is provided on the antenna conductor 2 as required. The case where the auxiliary antenna conductor 3 is provided is preferable because the reception sensitivity is improved by several dB as compared with the case where the auxiliary antenna conductor 3 is not provided. In FIG. 1, the auxiliary antenna conductor 3 is provided inside the antenna conductor 2. However, the present invention is not limited to this, and may be provided outside the antenna conductor 2.

The conductor lengths of the antenna conductor 2, the auxiliary antenna conductor 3, and the parasitic conductors 4a and 4b are respectively defined assuming that the wavelength of the center frequency of the desired reception frequency band is λ.
The range of (λ / 4) × K to 2λ × K is desirable. When it is within this range, the receiving sensitivity is improved by several dB as compared with the case where it is outside this range.

In the present invention, at least one of the antenna conductor and the auxiliary antenna conductor is capacitively coupled to the parasitic conductor, and the parasitic conductor and the vehicle body opening are capacitively coupled. Therefore, the antenna conductor and the auxiliary antenna conductor are capacitively coupled to the vehicle body opening through the parasitic conductor. The shortest distance between the parasitic conductor and the vehicle body opening is usually 50 mm or less.

The resonance frequency of the vehicle body opening is determined by the length of the vehicle body opening, but the peripheral length of the vehicle body opening is not particularly limited. However, it is preferable that the vehicle body opening resonates at a frequency higher than the lowest frequency of the desired reception frequency band (for example, 76 MHz or more in the case of the FM broadcast band) because the reception sensitivity is improved.

The vehicle body opening has a frequency higher than the highest frequency of the desired reception frequency band (for example, 90 Hz in the FM broadcast band).
It is more preferable to resonate at a frequency of at least MHz, since the receiving sensitivity is improved, and furthermore, the opening of the vehicle body is 120% of the highest frequency of the desired receiving frequency band (for example, the highest frequency is 90 MHz in the FM broadcasting band). , 108MHz or higher)
Resonating at a higher frequency improves reception sensitivity and is particularly preferable.

In the present invention, when the vehicle body opening resonates at a frequency higher than the lowest frequency of the desired reception frequency band, the case where the parasitic conductor is provided is generally more in comparison with the case where the parasitic conductor is not provided. The reception sensitivity is improved by 1 dB or more.

When the vehicle body opening resonates at a frequency higher than the highest frequency in the desired reception frequency band, the reception sensitivity is usually 2 dB or more when the parasitic conductor is provided as compared with the case where the parasitic conductor is not provided. Is improved.

When the opening of the vehicle body resonates at a frequency higher than 120% of the highest frequency in the desired reception frequency band, the case where the parasitic conductor is provided is usually 3 dB in comparison with the case where the parasitic conductor is not provided. As described above, the receiving sensitivity is improved.

Therefore, the preferred range of the length around the vehicle body opening is equal to or less than the wavelength of the lowest frequency in the desired reception frequency band. For example, if the desired reception frequency band is the FM broadcast band, the lowest frequency is 76 MHz,
A more preferred range of the perimeter of the vehicle body opening is 3947
mm or less.

A more preferable range of the length around the opening of the vehicle body is equal to or less than the wavelength of the highest frequency in the desired reception frequency band. For example, when the desired reception frequency band is the FM broadcast band, the highest frequency is 90 MHz, so the more preferable range of the length around the vehicle body opening is 3333 mm or less.

A particularly preferable range of the circumference of the vehicle body opening is 120 nm of the wavelength of the highest frequency in the desired reception frequency band.
% Or less. For example, when the desired receiving frequency band is the FM broadcasting band, the frequency higher than 120% of the highest frequency is 108 MHz, and the particularly preferable range of the length around the vehicle body opening is 2778 mm or less.

In order to improve the receiving sensitivity, an antenna conductor,
In at least one of the auxiliary antenna conductor and the parasitic conductor,
One or a plurality of phase adjustment elements having a substantially T-shaped, substantially L-shaped, or loop shape may be provided.

In the present invention, the vehicle body opening means an opening of the vehicle body into which the window glass plate is to be fitted, which is to serve as a vehicle body ground and is made of a conductive material such as metal.

In the present invention, it is preferable that the window glass plate provided with the antenna conductor has a small vehicle body opening. This is because resonance occurs at a frequency higher than the lowest frequency of the FM broadcast band. For this reason, the side window glass plate, particularly the rear side window glass plate, is most suitable for improving the receiving sensitivity. However, it is not limited to the side window glass plate, and may be a rear window glass plate, a front window glass plate, a roof window glass plate, or the like.

The glass antenna of the present invention may be provided on one side of a vehicle, for example, on a side window glass plate. But,
It is preferable to provide the antenna on both side window glass plates and perform diversity reception between both glass antennas in order to improve directivity. The preamplifier 9 is provided as needed, and contributes to improvement in reception sensitivity. However, if the receiving sensitivity is sufficiently large, it is not necessary to provide the receiving sensitivity.

The position of the feeding point 6 is not particularly limited in terms of reception characteristics, but is preferably provided as close as possible to the periphery of the window glass plate in order to ensure visibility. In FIG. 1, the feeding point 6 is provided on the upper left peripheral edge of the side window glass plate 1. However, the present invention is not limited to this, and it may be provided at any position of the side window glass plate 1, for example, may be provided at the upper and lower peripheral edges of the left and right center of the side window glass plate 1.

For the antenna conductor, the auxiliary antenna conductor, the parasitic conductor, and the conductor pattern of the feeding point, a silver paste printed on a window glass plate and fired is usually used. However, the present invention is not limited to this, and other metal pastes may be used, and a metal wire such as copper, a metal plate or a metal foil may be bonded to the window glass plate with an adhesive or the like.

The antenna conductor provided on the window glass plate can be applied to an AM radio broadcasting band, an FM radio broadcasting band, a television VHF band, a television UHF band, etc., and is not particularly limited. However, for FM radio broadcasting band, TV VH
The use in the F band is preferable because the reception sensitivity is improved.

Also, in the present invention, the number of antenna conductors provided for a vehicle is not limited, and the diversity between the glass antenna of the present invention and another antenna such as a pole antenna, another glass antenna, or the like. Reception may be performed.

FIGS. 5 to 7 show another type of the present invention, which is different from FIG. 5 to 7, the same components or members as those in FIG. 1 are denoted by the same reference numerals and description thereof will be omitted. 5 to 7, the lead wire 8, the preamplifier 9, and the coaxial cable 10 are not shown.

In FIG. 5, the antenna conductor 2 has a loop shape, and the auxiliary antenna conductor 3 has a half loop shape. The parasitic conductors 4a and 4b are in the form of two half loops, and the connecting conductor 5a is one.

In FIG. 6, the antenna conductor 2 has a loop shape and the auxiliary antenna conductor 3 has a half loop shape. The parasitic conductors 4a and 4b are in the form of two loops, and have no connection conductor.

In FIG. 7, both the antenna conductor 2 and the auxiliary antenna conductor 3 are formed in a half loop. Parasitic conductor 4a
Is a loop shape, 4b is a half loop shape, and no connection conductor is provided.

[0046]

EXAMPLES Example 1 (Example) A glass antenna for a vehicle as shown in FIG. 1 was manufactured. The side window glass plate 1 was the one on the left side of the vehicle, and the same one as shown in FIG. The size of the side window glass plate 1 is approximately 450 mm in the vertical direction,
Approximately 800 mm in the lateral direction, the length around the opening of the vehicle body is 250
0 mm. Therefore, the resonance frequency of the vehicle body opening was 120 MHz.

The conductor length of the antenna conductor 2 is 1000 mm,
The conductor width of the antenna conductor 2 is 0.4 mm, the conductor length of the auxiliary antenna conductor 3 is 1500 mm, the conductor lengths of the parasitic conductors 4a and 4b are 1700 mm and 1900 mm, respectively, and the conductor widths of the parasitic conductors 4a and 4b are 0.4 mm. The distance between the conductors was 25 mm. However, the interval L was 5 mm.
The shortest distance between the parasitic conductor 4b and the vehicle body opening was 30 mm. Feeding point 6 is square and its size is 15 mm x 1
5 mm.

FIG. 2 shows the frequency characteristics of the antenna reception sensitivity. As can be seen from FIG. 2, the reception sensitivity is high in the FM broadcast band.

Example 2 (Example) A vehicle glass antenna having exactly the same specifications as in Example 1 except that the interval L was changed was manufactured. FIG. 8 shows a sensitivity characteristic in which the frequency is 83 MHz and the interval L is a parameter.

[0050]

According to the present invention, since a part or all of the parasitic conductor is provided between the antenna conductor and the vehicle body opening, the vehicle body opening hardly affects the reception characteristics of the antenna conductor. Therefore, for example, even when the vehicle body opening is small and the vehicle body opening resonates in a frequency range other than the desired reception frequency band, the reception characteristics of the antenna conductor are hardly affected, and the reception sensitivity is small. Can be improved.

When the vehicle body opening resonates in a desired reception frequency band, flatness of reception sensitivity can be ensured in the reception frequency band. Further, since the conductor width of the parasitic conductor is 0.1 to 0.8 mm, a good field of view can be secured even when the vehicle body opening is small. When the present invention is applied to a small window glass plate such as a side window glass plate of an automobile, it is possible to improve reception sensitivity particularly in a high frequency band such as FM broadcasting and television VHF band.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a typical example of a glass antenna for a vehicle according to the present invention.

FIG. 2 is a diagram showing frequency characteristics of reception sensitivity of the representative example of FIG. 1;

FIG. 3 is a configuration diagram of a conventional example.

FIG. 4 is a frequency characteristic diagram of the receiving sensitivity of the conventional example of FIG. 3;

FIG. 5 is a block diagram of another type of the present invention different from FIG. 1;

FIG. 6 is a block diagram of another type of the present invention different from FIG. 1;

FIG. 7 is a block diagram of another type of the present invention different from FIG. 1;

FIG. 8 is a sensitivity characteristic diagram in which the frequency is 83 MHz and the interval L is a parameter in Example 2.

FIG. 9 is a configuration diagram of a conventional example of another type different from FIG.

[Explanation of symbols]

 1: Side window glass plate 2: Antenna conductor 3: Auxiliary antenna conductor 4a, 4b: Parasitic conductor 5a, 5b: Connection conductor 6: Feeding point 7: Body opening 8: Lead wire 9: Preamplifier 10: Coaxial cable L: interval

Claims (4)

[Claims] A power supply point provided on a window glass plate of a vehicle;
An antenna conductor connected to the feeding point and a plurality of parasitic conductors not connected to the feeding point are provided, and some or all of the parasitic conductor is provided between the antenna conductor and the vehicle body opening, A vehicle glass antenna, wherein the antenna conductor has a loop shape or a semi-loop shape, and the conductor width of the parasitic conductor is 0.1 to 0.8 mm. 2. The distance between the antenna conductor and the parasitic conductor is 10
The glass antenna for vehicles according to claim 1, which is not more than mm. 3. The glass antenna for a vehicle according to claim 1, wherein the plurality of parasitic conductors are connected to each other by a connection line. 4. The glass antenna for a vehicle according to claim 1, wherein the vehicle body opening resonates at a frequency higher than a lowest frequency of a desired reception frequency band.