JP6829735B2 - In-vehicle antenna device - Google Patents

Description

The present invention relates to an in-vehicle antenna device, and more particularly to an in-vehicle antenna device having noise immunity.

Antenna devices corresponding to a plurality of frequency bands installed in a vehicle, for example, antenna devices corresponding to the AM / FM band include various types such as pillar antennas, roof mount antennas, and glass antennas. However, a pillar antenna having a large amount of protrusion is likely to be bent due to contact or the like. In addition, since the roof mount antenna has a high ground clearance, it needs to be tilted or removed in a multi-storey car park or an automatic car wash machine. In addition, the glass antenna requires unique development for each vehicle model, and there is a problem that the development cost and the like increase. In recent years, there are also small and low-profile antenna devices such as so-called shark fin antennas. Further, an in-vehicle antenna device is required to not spoil the aesthetic appearance of the vehicle as much as possible, and various so-called spoiler antennas built in the spoiler so as not to spoil the appearance have been developed (for example, Patent Document 1).

In the case of shark fin antennas and roof mount antennas installed on the vehicle roof, noise from electronic devices placed in the vehicle causes problems because if the vehicle roof is a metal body, it is shielded by the vehicle roof. Hateful. However, in the case of the spoiler antenna, unlike the case where it is installed on the vehicle roof, it is installed in a place such as the upper part of the rear glass around the vehicle roof, so that the noise shielding effect of the vehicle roof cannot be expected. In the current in-vehicle antenna device, the noise level of the antenna for the FM frequency band is market-compatible and practical, but the noise level is often unacceptable for the antenna for the AM frequency band. Noise countermeasures are often required. For the purpose of shielding such noise from the inside of the vehicle, for example, there is also Japanese Patent Application No. 2018-172263 by the same applicant as the applicant of the present application. This is provided with a shielding plate between the shared antenna element in the AM / FM frequency band and the noise generation source in the vehicle.

Japanese Unexamined Patent Publication No. 2011-035519

However, although the patent application by the same applicant as the above-mentioned applicant of the present application has a high noise shielding effect, it is possible to avoid an increase in size as compared with an antenna device having no shielding plate because a shielding plate is used to obtain the shielding effect. There wasn't. Further, especially considering the sensitivity of the FM frequency band, it is necessary to secure a certain distance between the shared antenna element of the AM / FM frequency band and the shielding plate, specifically, about 30 mm, so that the application needs to be thinned. When applied to, it was necessary to take predetermined measures for the sensitivity of the FM frequency band.

In view of such circumstances, the present invention intends to provide an in-vehicle antenna device that has a noise shielding effect and can be made thinner.

In order to achieve the above-described object of the present invention, the in-vehicle antenna device according to the present invention has a first element, which is a capacitive antenna corresponding to the first frequency band, and a position for shielding noise from a noise source with respect to the first element. It is provided with a second element which is a resonance antenna corresponding to a second frequency band higher than the first frequency band while shielding noise.

Further, it may be provided with an attenuation circuit connected to the second element and attenuating the signal in the first frequency band.

Further, the first element may be made of a plate-shaped body, and the second element may be made of a plate-shaped body having a larger area than the first element.

Further, it may be provided with a first filter circuit connected to the first element and passing a signal in the first frequency band.

Further, it may be provided with a second filter circuit connected to the second element and passing a signal in the second frequency band.

Further, it is sufficient that the first element corresponds to the AM wave band and the second element corresponds to the FM wave band.

Further, it may be connected to the second element and provided with a resonance coil for tuning the second element to the signal of the second frequency band.

Further, it may be connected to the second element and include a plurality of resonance coils for tuning the second element to signals in a plurality of frequency bands.

Further, it may be provided with a circuit board on which an amplifier circuit for amplifying a signal in the first frequency band and / or a second frequency band is mounted.

Here, the circuit board may be arranged between the first element and the second element.

Further, it may be provided with a third element which is a patch antenna corresponding to the third frequency band.

Here, the third element may be arranged between the first element and the second element, and the first element may have a waveguide with respect to the third element.

Further, it may be provided with a fourth element, which is a dipole antenna that partially uses the second element, so as to correspond to a fourth frequency band higher than the second frequency band.

Further, it may be provided with a fifth element, which is a dipole antenna that partially uses the first element, so as to correspond to a fourth frequency band higher than the second frequency band.

Further, the second element may have a bracket shape for fixing to the resin portion of the vehicle.

Further, it is arranged near the side of the first element and includes a sixth element corresponding to the fifth frequency band, and the second element is a position for shielding noise from a noise source with respect to the first element and the sixth element. It may be arranged in and shields noise.

Further, it may be provided with an attenuation circuit which is connected to the second element and attenuates the signal of the first frequency band and the signal of the fifth frequency band.

Further, it is arranged near the side of the second element and includes a sixth element corresponding to the fifth frequency band, and at least one of the second element and the sixth element is from a noise source for the first element. It may be arranged at a position to shield noise and shield noise.

Further, it may be provided with an attenuation circuit connected to the sixth element and attenuating the signal in the first frequency band.

The in-vehicle antenna device of the present invention has an advantage that it has a noise shielding effect and can be made thinner.

FIG. 1 is a schematic perspective view for explaining an outline of the in-vehicle antenna device of the present invention. FIG. 2 is a schematic perspective view for explaining an example in which the shielding effect of the in-vehicle antenna device of the present invention is enhanced. FIG. 3 is a circuit diagram for explaining an example of an attenuation circuit used in the in-vehicle antenna device of the present invention. FIG. 4 is a schematic perspective view for explaining a specific example of the vehicle-mounted antenna device of the present invention. FIG. 5 is a schematic perspective view for explaining another specific example of the vehicle-mounted antenna device of the present invention. FIG. 6 is a schematic perspective view for explaining another example of the vehicle-mounted antenna device of the present invention. FIG. 7 is a schematic perspective view for explaining another example of the vehicle-mounted antenna device of the present invention. FIG. 8 is a schematic perspective view for explaining another example of the element of the in-vehicle antenna device of the present invention. FIG. 9 is a schematic perspective view for explaining another example of the element of the in-vehicle antenna device of the present invention. FIG. 10 is a schematic perspective view for explaining still another example of the element of the in-vehicle antenna device of the present invention. FIG. 11 is a schematic perspective view for explaining an example in which the elements of the vehicle-mounted antenna device of the present invention are configured in a grid pattern.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the illustrated examples. FIG. 1 is a schematic perspective view for explaining an outline of the in-vehicle antenna device of the present invention. As shown in the figure, the vehicle-mounted antenna device of the present invention is mainly composed of a first element 10 and a second element 20. The details will be described below.

The first element 10 is composed of a capacitive antenna corresponding to the first frequency band. The first frequency band may be, for example, the AM frequency band of a radio. The capacitive antenna is a so-called capacitive loaded antenna element. The first element 10 is a plate-like body in the illustrated example. Specifically, for example, in the case of the AM frequency band, the first element 10 may be made of a conductor having a flat plate shape of about 30 mm × 170 mm. However, the present invention is not limited to this, as long as it functions as a capacitively loaded antenna element having an antenna capacitance substantially equivalent to a solid pattern, and may have an umbrella shape instead of a planar shape. Further, various shapes such as a meander shape, a spiral shape, and a space-filling curve shape can be applied. However, when slits are provided to form a meander shape or the like, the intervals are preferably sufficiently small with respect to the wavelength of the first frequency band.

The second element 20 is a resonant antenna corresponding to a second frequency band higher than the first frequency band. The second frequency band may be, for example, the FM frequency band of a radio. The element length of the second element 20 may be adjusted so that the second element 20 functions as a resonance antenna. In the illustrated example, a plate-like body is shown. Specifically, for example, in the case of the FM frequency band, the second element 20 may be made of a conductor having a flat plate shape of about 50 mm × 180 mm. As will be described later, if the element length is insufficient for the FM frequency band, a resonance coil may be provided separately. The most characteristic point of the present invention is that the second element 20 is arranged at a position for shielding the noise from the noise source with respect to the first element 10 and has a function of shielding the noise. .. For example, when the noise source is a high mount stop lamp, the second element 20 may be arranged between the first element 10 and the high mount stop lamp. The second element 20 does not necessarily have to be larger than the first element 10 depending on the positional relationship between the noise source and the first element 10 and the second element 20 because it is sufficient to shield the noise from the noise source. However, if the second element 20 has an area larger than that of the first element 10, the second element 20 can have a shielding function against a plurality of noises from a plurality of noise sources, for example. It becomes. Further, if the second element 20 is arranged so as to be positioned perpendicular to the expected main noise source, noise can be shielded more efficiently. Therefore, the first element 10 and the second element 20 do not necessarily have to be arranged in parallel. Further, the second element 20 does not have to be a flat plate-like body, and has a semi-cylindrical shape, a concave shape, or a V-shape so as to cover the back surface side of the first element 10 or to match the shape of the installation location. Etc. may be used. Further, the second element 20 is a plate-like body in the illustrated example. However, the present invention is not limited to this, and various shapes such as a meander shape, a spiral shape, and a space-filling curve shape can be applied as long as they have a noise shielding function. However, when slits are provided to form a meander shape or the like, the intervals are preferably sufficiently small with respect to the wavelength of the first frequency band so as to have a noise shielding function.

The positional relationship between the first element 10 and the second element 20 may be appropriately fixed by using an insulating support member, a resin portion of the housing of the in-vehicle antenna device, or the like.

In the vehicle-mounted antenna device of the present invention configured as described above, the distance between the first element 10 and the second element 20 can be reduced. That is, in the second element 20, the first element 10 is arranged in the vicinity, but since the first element 10 is not grounded, it does not pose a big problem in ensuring the sensitivity of the second element 20. Therefore, in the vehicle-mounted antenna device of the present invention, the distance between the first element 10 and the second element 20 can be determined in consideration of only the sensitivity of the first element 10. Specifically, for example, in the case of the AM / FM frequency band, if there is a distance of about 10 mm, it is possible to secure an acceptable sensitivity for each of the first element 10 and the second element 20.

As described above, in the in-vehicle antenna device of the present invention, the second element 20 has a noise shielding effect on the first element 10 for the AM frequency band, that is, the first frequency band, in which the noise level is often unacceptable. By using the second element 20 as an element for the FM frequency band, it is possible to reduce the thickness while supporting a plurality of frequency bands. Therefore, the in-vehicle antenna device of the present invention can be easily arranged in a thin space such as a vehicle spoiler.

Further, in the in-vehicle antenna device of the present invention, since the first element 10 is used as an element for the AM frequency band and the second element 20 is used as an element for the FM frequency band, each element is in an independent state. ing. Therefore, unlike the case where the conventional shared antenna element of the AM / FM frequency band is used, a separation circuit for separating the AM signal and the FM signal becomes unnecessary. Therefore, there is no signal loss due to the separation circuit, and the overall antenna characteristics are improved.

Next, a method for enhancing the shielding effect of the second element 20 with respect to the first element 10 will be described below. FIG. 2 is a schematic perspective view for explaining an example in which the shielding effect of the in-vehicle antenna device of the present invention is enhanced. In the figure, the parts having the same reference numerals as those in FIG. 1 represent the same objects. In the illustrated example, the second element 20 has a bracket shape 25 for fixing to a resin member, such as a resin portion of a vehicle or a resin portion of a housing of an in-vehicle antenna device. Specifically, the bracket shape 25 is formed by making a notch or the like in the second element 20 and bending or the like. This is such that when the in-vehicle antenna device of the present invention is installed on a resin member such as a resin back door or a spoiler, the second element 20 can be directly fixed to the resin member with screws or the like. .. However, the present invention is not limited to this, and as described above, any device may be used as long as it functions as a capacitively loaded antenna element having an antenna capacitance substantially equivalent to that of a solid pattern.

As shown in FIG. 2, the second element 20 is connected to an attenuation circuit 21 that attenuates a signal in the first frequency band corresponding to the first element 10. As a result, among the noise from the noise generation source, the noise signal in the first frequency band is attenuated through the attenuation circuit 21 connected to the second element. Therefore, the second element 20 surely has a noise shielding function with respect to the first element 10.

The attenuation circuit 21 may be any one that attenuates the signal in the first frequency band. Specifically, for example, a noise filter circuit as shown in FIG. 3 may be used. FIG. 3 is a circuit diagram for explaining an example of an attenuation circuit used in the in-vehicle antenna device of the present invention, FIG. 3 (a) is a short-circuit circuit, and FIG. 3 (b) is an example of a high-pass filter circuit. is there. For example, when the short-circuit circuit of FIG. 3A is used as the attenuation circuit 21, the signal of the first frequency band flows to the ground side via the coil. As a result, the noise signal from the noise source for the first element 10 is grounded to the ground, the signal in the first frequency band is short-circuited, and the signal in the second frequency band flows to the output terminal OUT2 side. become. Further, even when the high-pass filter circuit of FIG. 3B is used as the attenuation circuit 21, the signal of the first frequency band, which is a frequency band lower than the second frequency band, flows to the ground side via the coil. It should be designed to. As a result, the noise signal from the noise source for the first element 10 is grounded to the ground, and the signal of the second frequency band, which is a frequency band higher than the first frequency band, flows to the output terminal OUT2 side. become. That is, the signal of the first frequency band reaching the second element 20 is grounded to the ground. As a result, the noise signal in the first frequency band is reliably attenuated. In the illustrated example, an example in which the attenuation circuit 21 is connected in series with the output terminal OUT2 of the second element 20 is shown, but the present invention is not limited to this, and the coil grounded to the ground is used as the attenuation circuit 21. It may be directly connected to the second element 20. Further, the attenuation circuit 21 may simply have a capacitor inserted in series with the output terminal OUT2. The inductance and capacitance may be appropriately adjusted according to the frequency band.

Further, a specific example of the in-vehicle antenna device of the present invention will be described with reference to FIG. FIG. 4 is a schematic perspective view for explaining a specific example of the vehicle-mounted antenna device of the present invention. In the figure, the parts with the same reference numerals as those in FIG. 2 represent the same objects. As shown in the figure, the in-vehicle antenna device of the present invention may further include a first filter circuit 12. The first filter circuit 12 is connected to the first element 10. Further, the first filter circuit 12 passes a signal in the first frequency band. Specifically, the first filter circuit 12 may be, for example, a low-pass filter circuit. By inserting the first filter circuit 12 in series with the output terminal OUT1, it is possible to output only the signal of the first frequency band to the output terminal OUT1. As a result, for example, the signal of the second frequency band can be prevented from flowing to the output terminal OUT1, so that the isolation between the first element 10 and the second element 20 can be enhanced. Therefore, even if the first element 10 and the second element 20 are arranged in the vicinity, it is possible to prevent the sensitivity deterioration due to the interference in both frequency bands. In the illustrated example, the second element 20 can be made smaller than the first element 10 depending on the positional relationship between the noise source and the first element 10 and the second element 20. The second element may be larger, as in the case of.

Further, the in-vehicle antenna device of the present invention may further include a second filter circuit 22. The second filter circuit 22 passes a signal in the second frequency band. Specifically, the second filter circuit 22 may be, for example, a high-pass filter circuit. By inserting the second filter circuit 22 in series with the output terminal OUT2, it is possible to output only the signal of the second frequency band to the output terminal OUT2. As a result, for example, the signal of the first frequency band can be prevented from flowing to the output terminal OUT2 side, so that the isolation between the first element 10 and the second element 20 can be further enhanced. Therefore, even if the first element 10 and the second element 20 are arranged in the vicinity, it is possible to prevent the sensitivity deterioration due to the interference in both frequency bands. The attenuation circuit 21 may be shared as the second filter circuit 22.

Further, as shown in the illustrated example, an amplifier circuit 13 for amplifying a signal in the first frequency band and an amplifier circuit 23 for amplifying a signal in the second frequency band may be provided. The amplifier circuits 13 and 23 may be used to amplify the received signal.

Further, in the example shown in FIG. 4, the resonance coil 24 is connected to the second element 20. The resonance coil 24 is used to tune the second element 20 to a signal in the second frequency band. This is to adjust the reactance with the resonance coil 24 when the element length is not enough to tune to the signal of the second frequency band, whereby the second element 20 tunes to the signal of the second frequency band. It will be possible.

Further, as shown in FIG. 5, the resonance coil 24 may be capable of selectively connecting a plurality of coils. FIG. 5 is a schematic perspective view for explaining another specific example of the vehicle-mounted antenna device of the present invention. In the figure, the parts having the same reference numerals as those in FIG. 4 represent the same objects. As shown in the figure, in the vehicle-mounted antenna device of the present invention, a plurality of resonance coils 24 for tuning the second element 20 to signals in a plurality of frequency bands may be connected to the second element 20. In the illustrated example, a switch capable of selectively connecting a plurality of resonance coils 24 is used. With this configuration, it is possible to tune the second element 20 not only to the signal of the second frequency band but also to the signal of another frequency band.

FIG. 6 is a schematic perspective view for explaining another example of the vehicle-mounted antenna device of the present invention. In the figure, the parts having the same reference numerals as those in FIG. 1 and the like represent the same objects. As shown in the figure, the vehicle-mounted antenna device of the present invention has a circuit board 30. For example, amplifier circuits 13 and 23 for amplifying signals in the first frequency band and the second frequency band may be mounted on the circuit board 30. Further, the attenuation circuit 21, the resonance coil 24, the first filter circuit 12, the second filter circuit 22, and the like may be mounted on the circuit board 30.

Then, as shown in the illustrated example, the circuit board 30 may be arranged between the first element 10 and the second element 20. Since the distance between the first element 10 and the second element 20 is arranged so as not to cause capacitive coupling, it is possible to provide a certain amount of space. In the vehicle-mounted antenna device of the present invention, the circuit board 30 is arranged using this space. As a result, it is not necessary to separately provide an area for arranging the circuit board 30, so that an in-vehicle antenna device having a size corresponding to the area of the first element 10 and the second element 20 can be realized. Therefore, it is possible to reduce the size while maintaining the noise shielding effect.

Further, as shown in the illustrated example, another element such as a patch antenna may be provided. That is, the third element 40, which is a patch antenna, may be provided. The third element 40 may be any one corresponding to the third frequency band. The third element 40 may be, for example, a dielectric type patch antenna using circularly polarized waves using ceramics or the like. Specifically, for example, a patch antenna for GPS, GLONASS, SDARS, etc. having a resonance frequency in the UHF band or the like may be used. The third element 40 is not limited to the example of FIG. 6, and may of course be used together with other illustrated examples. The in-vehicle antenna device of the present invention can be configured to correspond to a plurality of frequency bands in this way.

Next, an example in which a patch antenna as disclosed in Japanese Patent Application Laid-Open No. 2018-121143 by the same applicant as the applicant of the present application is added to the in-vehicle antenna device of the present invention will be described with reference to FIG. FIG. 7 is a schematic perspective view for explaining another example of the vehicle-mounted antenna device of the present invention. In the figure, the parts having the same reference numerals as those in FIG. 1 and the like represent the same objects. As shown in the figure, the vehicle-mounted antenna device of the present invention is an example in which a third element 40, which is a patch antenna, is further provided. This third element is arranged between the first element 10 and the second element 20. The first element 10 has a waveguide 15 with respect to the third element. The waveguide portion 15 refers to a substantially square conductive planar portion that also functions as a director of the third element 40. By providing the waveguide 15, the gain of the third element 40 can be improved even if the third element 40 is arranged between the first element 10 and the second element 20. In the illustrated example, the waveguide 15 is formed by electrically dividing the rectangular first element 10 into a plurality of substantially square conductive planar bodies viewed from the third element 40 using stubs 16. Has been done. The stub 16 is formed by a folded pattern composed of a plurality of slits 17 provided alternately in the first element 10 so that the directions of the electric currents flow in directions that cancel each other out. By providing the plurality of slits 17 provided in a staggered manner, the directions of the currents cancel each other out in the periphery where the slits 17 are provided. As a result, in the third frequency band such as the UHF band of the third element 40, the first element 10 behaves as if it is divided into a plurality of substantially square blocks. With this configuration, the vehicle-mounted antenna device of the present invention does not need to separately provide an area for arranging the third element 40. Therefore, the vehicle-mounted antenna having a size corresponding to the area of the first element 10 and the second element 20. The device can be realized. Therefore, it is possible to reduce the size while maintaining the noise shielding effect. Since details of other specific examples of the waveguide are described in Japanese Patent Application Laid-Open No. 2018-121143 by the same applicant as the applicant of the present application, detailed description thereof will be omitted in the present application.

Next, an example in which a dipole antenna as disclosed in Japanese Patent Application No. 2018-136488 by the same applicant as the applicant of the present application is added to the in-vehicle antenna device of the present invention will be described with reference to FIG. FIG. 8 is a schematic perspective view for explaining another example of the element of the in-vehicle antenna device of the present invention. In the figure, the parts having the same reference numerals as those in FIG. 1 and the like represent the same objects. This example is an application of the in-vehicle antenna device of the present invention to an element sharing composite antenna device. The element sharing composite antenna device can receive signals of a plurality of frequency bands by using one element of the dipole antenna as a monopole antenna. As shown in the figure, the in-vehicle antenna device of the present invention of this example is a part of a dipole antenna 50 that partially uses the second element 20 so as to correspond to a fourth frequency band higher than the second frequency band. It has a fourth element 51. The second element 20, which is a monopole antenna, is a resonant antenna corresponding to a signal in the second frequency band, as in the above illustrated example, and may be, for example, an FM frequency band of a radio. Further, an example is shown in which a resonance coil 24 for tuning the second element 20 to a signal in the second frequency band is connected in series with the output terminal OUT2, but the resonance coil 24 is a signal in the second frequency band. However, it can be omitted if the element length is sufficient. Further, the inner conductor of the coaxial cable 1 is connected to the output terminal OUT2, and the outer conductor is grounded to the ground. The dipole antenna 50 is configured to correspond to a fourth frequency band higher than the second frequency band. The fourth frequency band may be, for example, a frequency band for digital television broadcasting (DTV) or the like. The dipole antenna 50 is not limited to that for DTV, and may be in the frequency band for DAB (BANDIII). Further, it may be a frequency band for mobile phones. The dipole antenna 50 uses the second element 20 as a part. That is, the dipole antenna 50 is composed of the second element 20 and the fourth element 51. The output terminal OUT3 branched from the second element 20 is a feeding portion for the dipole antenna 50, and is connected to the inner conductor of the coaxial cable 2. Further, the outer conductor of the coaxial cable 2 is grounded to the ground. Further, the fourth element 51 is connected to the outer conductor of the coaxial cable 2. That is, of the two elements of the dipole antenna 50, the second element 20 to which the inner conductor of the coaxial cable 2 is connected is the element shared as the monopole antenna. Since details of other specific examples are described in Japanese Patent Application No. 2018-136488 by the same applicant as the applicant of the present application, detailed description thereof will be omitted in the present application. When the second element 20 is an element for the FM frequency band, for example, the in-vehicle antenna device of the present invention has a large area to some extent, so that the antenna characteristics as a dipole antenna are also good.

Although FIG. 8 shows an example in which the second element 20 is used as a part of the dipole antenna 50, the present invention is not limited to this, and the first element 10 may be used as a part of the dipole antenna. good. That is, the in-vehicle antenna device of the present invention is a part of a dipole antenna that partially uses the first element 10 as an element-sharing composite antenna device so as to correspond to a fourth frequency band higher than the second frequency band. It may be provided with the fifth element. As described above, the fourth frequency band may be, for example, a frequency band for digital television broadcasting (DTV). In the in-vehicle antenna device of the present invention, for example, when the first element 10 is an element for the AM frequency band, the dipole antenna is located above the second element 20, so that the antenna characteristics as a dipole antenna are also good. It becomes.

Next, another example of the element of the vehicle-mounted antenna device of the present invention will be described with reference to FIG. FIG. 9 is a schematic perspective view for explaining another example of the element of the in-vehicle antenna device of the present invention. In the figure, the parts having the same reference numerals as those in FIG. 1 and the like represent the same objects. This example further has a sixth element 70 as compared to the above illustrated example. The sixth element 70 may be any one corresponding to the fifth frequency. The fifth frequency band may be, for example, a frequency band for TEL. The element length of the sixth element 70 may be adjusted so that the sixth element 70 functions as a resonance antenna. If the element length is insufficient, the reactance may be adjusted by using a coil or the like as appropriate. As shown in the figure, the sixth element 70 may be arranged near the side of the first element 10. The second element 20 is arranged at a position where noise from the noise generation source is shielded from the two elements of the first element 10 and the sixth element 70. In the illustrated example, an example in which the sixth element 70 is arranged flush with the first element 10 is shown, but the present invention is not limited to this, and the height may be different or the angle of the plane may be different. You may. Further, the first element 10 and the sixth element 70 do not have to be parallel. Further, in the illustrated example, the second element 20 is not a flat plate-like body, but is bent so as to have a V shape when viewed from the short side direction. However, the present invention is not limited to this, and a flat plate-like body may be used as long as it has a noise shielding function, as in the above illustrated example.

Further, the attenuation circuit 21 connected to the second element 20 may attenuate the signal in the first frequency band and / or the signal in the fifth frequency band. This makes it possible to enhance the shielding effect of the second element 20 with respect to the first element 10 and / or the sixth element 70.

In addition, another example of the element of the vehicle-mounted antenna device of the present invention will be described with reference to FIG. FIG. 10 is a schematic perspective view for explaining another example of the element of the in-vehicle antenna device of the present invention. In the figure, the parts having the same reference numerals as those in FIG. 1 and the like represent the same objects. This example further has a sixth element 70 as compared to the examples of FIGS. 1 and 2. The sixth element 70 may be any one corresponding to the fifth frequency. The fifth frequency band may be, for example, a frequency band for TEL. The element length of the sixth element 70 may be adjusted so that the sixth element 70 functions as a resonance antenna. If the element length is insufficient, the reactance may be adjusted by using a coil or the like as appropriate. As shown in the figure, the sixth element 70 is arranged near the side of the second element 20. Then, at least one of the second element 20 and the sixth element 70 may be arranged at a position that shields noise from the noise generation source with respect to the first element 10. In the illustrated example, an example in which the sixth element 70 is arranged flush with the second element 20 is shown, but the present invention is not limited to this, and the height may be different or the angle of the plane may be different. You may. Further, the second element 20 and the sixth element 70 do not have to be parallel. Further, the second element 20 and the sixth element 70 may be bent so as to have a V shape when viewed from the short side direction as shown in FIG.

In the illustrated example, an example in which the attenuation circuit 21 is connected to the second element 20 is shown so as to enhance the shielding effect of the second element 20. However, the present invention is not limited to this, and when the sixth element 70 is arranged so as to have a shielding effect on the first element 10, the attenuation that attenuates the signal in the first frequency band with respect to the sixth element 70. A circuit may be connected. This makes it possible to enhance the shielding effect of the sixth element 70 with respect to the first element 10. Further, an attenuation circuit may be connected to both the second element 20 and the sixth element 70.

As described above, in the vehicle-mounted antenna device of the present invention, the first element 10 and the second element 20 can have various shapes such as a meander shape, a spiral shape, and a space-filling curve shape. As an example, FIG. 11 shows an example in which a grid-like element is used. FIG. 11 is a schematic perspective view for explaining an example in which the elements of the vehicle-mounted antenna device of the present invention are configured in a grid pattern. In the figure, the parts having the same reference numerals as those in FIG. 1 and the like represent the same objects. As shown in the figure, the first element 10 and the second element 20 are each formed in a grid shape (mesh shape) using conductive wires. The distance between the first element 10 and the second element 20 may be appropriately fixed by using, for example, an insulating support member 60. With such a configuration, it is possible to reduce the weight of the element as compared with the conductor of the flat plate-like body. In the illustrated example, both the first element 10 and the second element 20 are configured in a grid pattern, but the present invention is not limited to this, and even if only one of them is configured in a grid pattern. Of course good. Further, although the second element 20 in the illustrated example is bent so as to have a V shape when viewed from the short side direction, it may be flat.

It should be noted that the in-vehicle antenna device of the present invention is not limited to the above-mentioned illustrated examples, and it goes without saying that various modifications can be made without departing from the gist of the present invention.

1 Coaxial cable 2 Coaxial cable 10 1st element 12 1st filter circuit 13 Amplifier circuit 15 Waveguide 16 Stub 17 Slit 20 2nd element 21 Attenuation circuit 22 2nd filter circuit 23 Amplifier circuit 24 Resonance coil 25 Bracket shape 30 circuit Board 40 3rd element 50 Dipole antenna 51 4th element 60 Support member 70 6th element

Claims (19)

An in-vehicle antenna device installed at a position where noise from a noise source is received in a vehicle having a noise source that generates noise , and the in-vehicle antenna device is
The first element, which is a capacitive antenna corresponding to the first frequency band,
It has a flat surface portion, and is arranged between the vehicle noise source and the first element at a position where noise from the vehicle noise source with respect to the first element is shielded by the surface portion surface with respect to the first element. The second element, which is a resonance antenna corresponding to the second frequency band higher than the first frequency band while blocking the noise from the noise source of the vehicle ,
An in-vehicle antenna device characterized by comprising. The vehicle-mounted antenna device according to claim 1, further comprising an attenuation circuit connected to the second element and attenuating a signal in the first frequency band. The vehicle-mounted antenna device according to claim 1 or 2, wherein the first element is made of a plate-shaped body, and the second element is made of a plate-shaped body having a larger area than the first element. In-vehicle antenna device. The vehicle-mounted antenna device according to any one of claims 1 to 3, further comprising a first filter circuit connected to the first element and passing a signal in the first frequency band. In-vehicle antenna device. The vehicle-mounted antenna device according to any one of claims 1 to 4, further comprising a second filter circuit connected to the second element and passing a signal in the second frequency band. In-vehicle antenna device. The vehicle-mounted antenna device according to any one of claims 1 to 5, wherein the first element corresponds to the AM wave band and the second element corresponds to the FM wave band. The vehicle-mounted antenna device according to any one of claims 1 to 6, further comprising a resonance coil connected to the second element and for tuning the second element to a signal in the second frequency band. An in-vehicle antenna device characterized by The vehicle-mounted antenna device according to any one of claims 1 to 6, further connected to the second element, and a plurality of resonance coils for tuning the second element to signals in a plurality of frequency bands. An in-vehicle antenna device characterized by comprising. The vehicle-mounted antenna device according to any one of claims 1 to 8, characterized in that it includes a circuit board on which an amplifier circuit for amplifying a signal in the first frequency band and / or a second frequency band is mounted. In-vehicle antenna device. The vehicle-mounted antenna device according to claim 9, wherein the circuit board is arranged between the first element and the second element. The vehicle-mounted antenna device according to any one of claims 1 to 10, further comprising a third element which is a patch antenna corresponding to a third frequency band. In the vehicle-mounted antenna device according to claim 11, the third element is arranged between the first element and the second element.
The first element has a waveguide with respect to the third element.
An in-vehicle antenna device characterized by this. The vehicle-mounted antenna device according to any one of claims 1 to 12, further comprising a dipole antenna that partially uses a second element so as to correspond to a fourth frequency band higher than the second frequency band. An in-vehicle antenna device including a fourth element. The vehicle-mounted antenna device according to any one of claims 1 to 12, further comprising a dipole antenna that partially uses the first element so as to correspond to a fourth frequency band higher than the second frequency band. An in-vehicle antenna device including a fifth element. The vehicle-mounted antenna device according to any one of claims 1 to 14, wherein the second element has a bracket shape for fixing to a resin portion of a vehicle. The vehicle-mounted antenna device according to any one of claims 1 to 15, further comprising a sixth element arranged near the side of the first element and corresponding to the fifth frequency band.
The second element is a position between the noise source of the vehicle and the first element and the sixth element, and shields the noise from the noise source of the vehicle with respect to the first element and the sixth element by the surface of the surface portion. Placed in to shield noise,
An in-vehicle antenna device characterized by this. The vehicle-mounted antenna device according to claim 16, further comprising an attenuation circuit connected to the second element and attenuating a signal in the first frequency band and / or a signal in the fifth frequency band. In-vehicle antenna device. The vehicle-mounted antenna device according to any one of claims 1 to 17, further having a flat surface portion, and being between a vehicle noise source and the first element, the second element. It is located near the side and has a sixth element corresponding to the fifth frequency band.
The sixth element is arranged at a position where the noise from the noise source of the vehicle with respect to the first element is shielded by the surface of the surface portion to shield the noise.
An in-vehicle antenna device characterized by this. The vehicle-mounted antenna device according to claim 18, further comprising an attenuation circuit connected to the sixth element and attenuating a signal in the first frequency band.