JP7031986B2 - Antenna unit - Google Patents

Description

The present invention relates to an antenna unit.

Conventionally, as an antenna unit, for example, Patent Document 1 discloses an antenna unit including a patch antenna that receives radio waves transmitted from ETC.

Japanese Unexamined Patent Publication No. 2007-128321

By the way, in the antenna unit described in Patent Document 1 described above, for example, when an antenna for receiving another radio wave is provided in addition to the patch antenna for receiving ETC radio waves, the antenna unit may become large in size. There is room for further improvement in terms of points.

Therefore, the present invention has been made in view of the above, and an object of the present invention is to provide an antenna unit capable of suppressing an increase in size.

In order to solve the above-mentioned problems and achieve the object, the antenna unit according to the present invention has a base material formed in a sheet shape and either a first right-handed circular polarization or a first left-handed circular polarization. The first outer conductor formed in an arc shape having a length corresponding to one wavelength of the above, and the first right-handed circular polarization or the first left-handed circular polarization provided inside the first outer conductor. A first inner conductor that consists of a length based on one of the other wavelengths and is formed in an arc shape to suppress interference between the circular polarization of either the first right-handed circular polarization or the first left-handed circular polarization. , A first antenna to which one end of the first outer conductor and one end of the first inner conductor are connected, and either a second right-handed circular polarization or a second left-handed circular polarization. A second outer conductor having a length corresponding to one wavelength of the above and formed in an arc shape, and the second right-handed circularly polarized wave or the second left-handed circularly polarized wave provided inside the second outer conductor. A second inner conductor that consists of a length based on one of the other wavelengths and is formed in an arc shape to suppress interference between the circular polarization of either the second right-handed circular polarization or the second left-handed circular polarization. The second antenna is configured to include, and one end of the second outer conductor and one end of the second inner conductor are connected to each other, and the first antenna is provided on one surface of the base material. The second antenna is provided on the other side surface of the base material, and the first outer conductor and the second outer conductor have a concentric arc shape centered on the central axis, and the first outer conductor is provided. The second inner conductor is concentric arcuate with the central axis as the center, and is characterized in that the second inner conductors overlap each other when viewed from the axial direction along the central axis.

In the antenna unit, the length of the second inner conductor is in the range of 13 / 18L to 14 / 18L, where L is the length of the first outer conductor.

In the antenna unit, the other end of the first inner conductor is located inside the first outer conductor in a disconnected state, and the other end of the second inner conductor is of the second outer conductor in a disconnected state. Located inside.

In the antenna unit, in the first outer conductor, a current flows between one end of the first outer conductor and the other end of the first outer conductor, and the first inner conductor is viewed from the axial direction. A current flows between one end of the first inner conductor and the other end of the first inner conductor in the direction opposite to that of the first outer conductor, and the second outer conductor has a current flowing through one end of the second outer conductor. And the other end of the second outer conductor, the second inner conductor has a current between one end of the second inner conductor and the other end of the second inner conductor when viewed from the axial direction. Flows in the direction opposite to that of the second outer conductor.

In the antenna unit according to the present invention, the first and second antennas are provided on one side or the other side of the base material, respectively, and the first and second outer conductors have a concentric arc shape, and the first outer conductor and the second outer conductor are formed. The inner conductors are concentric arcs and overlap each other. With this configuration, the antenna unit can be arranged so that the first and second antennas can be placed on the front and back of the base material in a state where two different radio waves can be received, so that the increase in size of the antenna unit can be suppressed. can.

FIG. 1 is a plan view showing a configuration example of an antenna unit according to an embodiment. FIG. 2 is a plan view showing a configuration example of the antenna unit according to the embodiment. FIG. 3 is a diagram showing the gain of the antenna unit according to the embodiment. FIG. 4 is a diagram showing VSWR of the antenna unit according to the embodiment. FIG. 5 is a Smith chart showing the impedance characteristics of the ETC antenna according to the embodiment. FIG. 6 is a Smith chart showing the impedance characteristics of the GPS antenna according to the embodiment. FIG. 7 is a diagram showing an axial ratio of the antenna unit according to the embodiment. FIG. 8 is a diagram showing the directivity characteristics of the ETC antenna according to the embodiment. FIG. 9 is a diagram showing the directivity characteristics of the GPS antenna according to the embodiment. FIG. 10 is a plan view showing a configuration example of the antenna unit according to the modified example of the embodiment. FIG. 11 is a plan view showing a configuration example of the antenna unit according to the modified example of the embodiment. FIG. 12 is a diagram showing VSWR of the antenna unit according to the modified example of the embodiment. FIG. 13 is a diagram showing the gain of the antenna unit according to the modified example of the embodiment.

An embodiment (embodiment) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiments. In addition, the components described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the configurations described below can be combined as appropriate. In addition, various omissions, substitutions or changes of the configuration can be made without departing from the gist of the present invention.

[Embodiment]
The antenna unit 100 according to the embodiment will be described. The antenna unit 100 receives a plurality of radio waves, for example, right-handed circular polarization (first right-handed circular polarization) of ETC (Electronic Tall Collection System) and right of GPS (Global Positioning System). Receives circularly polarized waves (second right-handed circularly polarized waves). The right-handed circular polarization of GPS has, for example, a frequency of 1.575 GHz. The right-handed circular polarization of ETC has, for example, a frequency of 5.8 GHz. The antenna unit 100 is mounted on a vehicle, for example, and is provided on the inside of the roof of the vehicle, on the installation surface of a dielectric such as a windshield and an instrument panel (resin member). The antenna unit 100 may be mounted on a vehicle other than the vehicle. Hereinafter, the antenna unit 100 will be described in detail.

As shown in FIG. 1, the antenna unit 100 includes, for example, an ETC antenna 1A, a GPS antenna 1B, and a film 2. The film 2 is an insulating member formed in a sheet shape. The film 2 is formed of, for example, PET (polyethylene terephthalate) and has a thickness of about 0.25 mm. An ETC antenna 1A is provided on the front surface 2a of the film 2, and a GPS antenna 1B is provided on the back surface 2b of the film 2. The film 2 is provided, for example, on an installation surface such as a windshield of a vehicle with the surface 2a facing the direction of arrival of radio waves.

The ETC antenna 1A is an antenna that receives the right-handed circular polarization of ETC. The ETC antenna 1A is formed by printing a conductor such as silver paste on the surface 2a of the film 2. The ETC antenna 1A is not limited to printing with silver paste or the like, and may be formed of conductive ink, a conductor thin film, or the like. As shown in FIG. 1, the ETC antenna 1A includes an outer conductor 10, feeder lines 21L and 21R, and an inner conductor 30. The outer conductor 10 is an antenna that receives the right-handed circular polarization of ETC. The outer conductor 10 includes a feeding point 11L as the other end of the first outer conductor, a feeding point 11R as one end of the first outer conductor, and an outer main body portion 12. In the present embodiment, for example, the feeding point 11L is a positive electrode and the feeding point 11R is a negative electrode. The outer main body portion 12 is a portion in which the first outer conducting wire is formed in an arc shape (circular shape) from the feeding point 11L to the feeding point 11R. The outer main body portion 12 has a length corresponding to one wavelength of the right-handed circular polarization of ETC. The outer main body portion 12 has a gap between the feeding point 11L and the feeding point 11R in the circumferential direction.

In the outer conductor 10, a current flows between the feeding point 11L and the feeding point 11R along the circumferential direction of the outer main body portion 12. In the present embodiment, since the outer conductor 10 receives the right-handed circular polarization of the ETC, a current flows clockwise between the feeding point 11L and the feeding point 11R when the surface 2a of the film 2 is viewed. That is, when the outer conductor 10 receives the right-handed circular polarization of ETC, a current flows from the feeding point 11L of the positive electrode to the feeding point 11R of the negative electrode.

The feeder lines 21L and 21R are conductive lines through which the current received by the outer main body 12 flows. One end of the feeder line 21L is connected to the feeding point 11L of the outer conductor 10, and the other end is connected to a receiving circuit (not shown). One end of the feeder line 21R is connected to the feeding point 11R of the outer conductor 10, and the other end is connected to the receiving circuit. The feeder lines 21L and 21R pass the current received by the outer main body 12 to the receiving circuit.

The inner conductor 30 is a portion that suppresses the ETC antenna 1A from receiving the left-handed circular polarization. That is, the inner conductor 30 is a portion that suppresses the left-handed circular polarization of ETC from interfering with the right-handed circular polarization of ETC. The inner conductor 30 is provided inside the outer conductor 10, and includes an inner main body portion 31 and a connecting portion 32. The inner main body portion 31 and the connecting portion 32 are formed from the first inner conducting wire, and have a length based on one wavelength of the left-handed circular polarization of ETC. In the inner main body portion 31, the inner end 31R of the first inner conductor is connected to the feeding point 11R of the negative electrode via the connecting portion 32, and the inner other end 31L of the first inner conductor is not connected to the inside of the outer conductor 10. To position. The inner main body portion 31 is formed in an arc shape (circular shape) from the inner one end 31R to the inner other end 31L. The inner main body portion 31 has a gap between the inner one end 31R and the inner other end 31L in the circumferential direction.

When viewed from the axial direction of the inner conductor 30, a current flows between the inner end 31R and the inner other end 31L in the direction opposite to that of the outer conductor 10. In the inner conductor 30, for example, a current flows from the inner one end 31R toward the inner other end 31L along the circumferential direction of the inner main body portion 31. That is, the inner conductor 30 looks at the surface 2a of the film 2 and a current flows counterclockwise from the inner one end 31R toward the inner other end 31L in the disconnected state.

The connecting portion 32 is a portion that connects the inner one end 31R of the inner main body portion 31 and the feeding point 11R of the outer conductor 10. The connecting portion 32 extends along the radial direction of the outer conductor 10. In the connecting portion 32, a current flows between the inner end 31R of the inner main body portion 31 and the feeding point 11R of the outer conductor 10.

The GPS antenna 1B is an antenna that receives the right-handed circular polarization (second right-handed circular polarization) of GPS. The GPS antenna 1B is formed by printing a conductor such as silver paste on the back surface 2b of the film 2, for example. The GPS antenna 1B is not limited to printing with silver paste or the like, and may be formed of conductive ink, a conductor thin film, or the like. As shown in FIG. 2, the GPS antenna 1B includes an outer conductor 40, feeder lines 51L and 51R, and an inner conductor 60. The outer conductor 40 is an antenna that receives the right-handed circular polarization of GPS. The outer conductor 40 includes a feeding point 41L as the other end of the second outer conductor, a feeding point 41R as one end of the second outer conductor, and an outer main body portion 42. In the present embodiment, for example, the feeding point 41L is a positive electrode and the feeding point 41R is a negative electrode. The outer main body portion 42 is a portion in which the second outer conducting wire is formed in an arc shape (circular shape) from the feeding point 41L to the feeding point 41R. The outer main body portion 42 has a length corresponding to one wavelength of the right-handed circular polarization of GPS. The radius of the outer main body 42 is different from the radius of the outer main body 12 of the ETC antenna 1A. The outer main body portion 42 is formed in a concentric arc shape (concentric circle shape) with the outer main body portion 12 of the ETC antenna 1A about the central axis. That is, the outer main body 42 shares the center with the outer main body 12 of the ETC antenna 1A. The outer main body portion 42 has a gap between the feeding point 41L and the feeding point 41R in the circumferential direction.

In the outer conductor 40, a current flows between the feeding point 41L and the feeding point 41R along the circumferential direction of the outer main body portion 42. In the present embodiment, since the outer conductor 40 receives the right-handed circular polarization of GPS, a current flows clockwise between the feeding point 41L and the feeding point 41R when looking at the back surface 2b of the film 2. That is, when the outer conductor 40 receives the right-handed circular polarization, a current flows from the feeding point 41L of the positive electrode to the feeding point 41R of the negative electrode.

The feeder lines 51L and 51R are conductive lines through which the current received by the outer main body 42 flows. One end of the feeder line 51L is connected to the feeding point 41L of the outer conductor 40, and the other end is connected to a receiving circuit (not shown). One end of the feeder line 51R is connected to the feeding point 41R of the outer conductor 40, and the other end is connected to the receiving circuit. The feeder lines 51L and 51R pass the current received by the outer main body 42 to the receiving circuit.

The inner conductor 60 is a portion that suppresses the GPS antenna 1B from receiving the left-handed circular polarization. That is, the inner conductor 60 is a portion that suppresses the left-handed circular polarization of GPS from interfering with the right-handed circular polarization of GPS. The inner conductor 60 is provided inside the outer conductor 40, and includes an inner main body portion 61 and a connecting portion 62. The inner main body portion 61 and the connecting portion 62 are formed from the second inner conducting wire, and have a length based on one wavelength of the left-handed circular polarization of GPS. In the inner main body portion 61, the inner end 61R of the second inner conductor is connected to the feeding point 41R of the negative electrode via the connecting portion 62, and the inner other end 61L of the second inner conductor is not connected to the inside of the outer conductor 40. To position. The inner main body portion 61 is formed in an arc shape from the inner one end 61R to the inner other end 61L. The radius of the inner main body 61 is equivalent to the radius of the outer main body 12 of the ETC antenna 1A. The inner main body portion 61 is formed in a concentric arc shape with the outer main body portion 12 of the ETC antenna 1A about the central axis. That is, the inner main body 61 shares the center with the outer main body 12 of the ETC antenna 1A. As a result, the inner main body 61 overlaps with the outer main body 12 when viewed from the axial direction along the central axis of the outer main body 12 of the ETC antenna 1A. In the inner main body 61, for example, all parts of the inner main body 61 overlap with a part of the outer main body 12 when viewed from the axial direction. That is, the inner main body 61 is laminated on the outer main body 12 via the film 2 along the axial direction of the outer main body 12 of the ETC antenna 1A. In other words, the inner main body 61 faces the outer main body 12 via the film 2 along the axial direction of the outer main body 12 of the ETC antenna 1A. The length of the inner main body portion 61 is, for example, 3/4 L, where L is the length of the outer main body portion 12 of the ETC antenna 1A. That is, the length of the inner main body 61 is a length corresponding to an arc portion of 270 ° on the outer circumference of the outer main body 12 of the ETC antenna 1A. The inner main body portion 61 has a predetermined distance between the inner one end 61R and the inner other end 61L.

When viewed from the axial direction of the inner conductor 60, a current flows between the inner one end 61R and the inner other end 61L in the direction opposite to that of the outer conductor 40. In the inner conductor 60, for example, a current flows from the inner one end 61R toward the inner other end 61L along the circumferential direction of the inner main body portion 61. That is, in the inner conductor 60, when the back surface 2b of the film 2 is viewed, a current flows counterclockwise from the inner one end 61R toward the inner other end 61L in the disconnected state.

The connecting portion 62 is a portion that connects the inner one end 61R of the inner main body portion 61 and the feeding point 41R of the outer conductor 40. The connecting portion 62 extends along the radial direction of the outer conductor 40. The connecting portion 62 extends along the same direction as the connecting portion 32 of the ETC antenna 1A, for example. The connecting portion 62 overlaps with a part of the feeder line 21L of the ETC antenna 1A via the film 2 when viewed from the axial direction of the outer main body portion 42. In the connecting portion 62, a current flows between the inner one end 61R of the inner main body portion 61 and the feeding point 41R of the outer conductor 40.

Next, the simulation result of the antenna unit 100 of the embodiment will be described. In the present embodiment, as the configuration of the antenna unit 100 in the simulation, the patterns of the ETC antenna 1A and the GPS antenna 1B are printed on the film 2 having a thickness of 0.25 mm with a silver paste having a thickness of 0.01 mm, and the top and bottom thereof are 0. It was configured to be sandwiched by a PET film having a thickness of 1 mm. The dielectric constant of the film 2 was set to "3".

FIG. 3 is a diagram showing the gain of the antenna unit 100, in which the vertical axis represents the gain (dB) and the horizontal axis represents the frequency (GHz). FIG. 3 illustrates the gain of right-handed circular polarization and the gain of left-handed circular polarization in the ETC antenna 1A, and the gain of right-handed circular polarization and left-handed circular polarization in the GPS antenna 1B. According to the simulation results shown in FIG. 3, the ETC antenna 1A has a gain of about -2.0 dB for right-handed circular polarization (P1 in the figure) and a gain of about -18.0 dB for left-handed circular polarization (FIG. 3). Medium P2). As a result, it can be seen that the ETC antenna 1A can satisfactorily receive the right-handed circularly polarized wave while suppressing the reception of the left-handed circularly polarized wave. The GPS antenna 1B has a right-handed circularly polarized wave gain of about 0 dB (P3 in the figure) and a left-handed circularly polarized wave gain of about −8.0 dB (P4 in the figure). As a result, it can be seen that the GPS antenna 1B can satisfactorily receive the right-handed circularly polarized wave after suppressing the reception of the left-handed circularly polarized wave.

FIG. 4 is a diagram showing VSWR (voltage standing wave ratio; Voltage Standing Wave Ratio) of the antenna unit 100, in which the vertical axis represents VSWR and the horizontal axis represents frequency (GHz). According to the simulation results shown in FIG. 4, it can be seen that the ETC antenna 1A has a VSWR of about 1.8 (P5 in the figure) and has relatively good power efficiency. It can be seen that the GPS antenna 1B has a VSWR of about 2.0 (P6 in the figure) and has relatively good power efficiency.

FIG. 5 is a Smith chart showing the impedance characteristics of the ETC antenna 1A. According to the simulation results shown in FIG. 5, it can be seen that the magnitude of the reflection is about 0.29, the phase is about 131 (P7 in the figure), and the reflection is relatively small.

FIG. 6 is a Smith chart showing the impedance characteristics of the GPS antenna 1B. According to the simulation results shown in FIG. 6, it can be seen that the magnitude of the reflection is about 0.07, the phase is about 69 (P8 in the figure), and the reflection is relatively small.

FIG. 7 is a diagram showing an axial ratio (AR; Axial Radio) of the antenna unit 100, in which the vertical axis represents the axial ratio and the horizontal axis represents the frequency (GHz). According to the simulation results shown in FIG. 7, it can be seen that the ETC antenna 1A has an axial ratio of about 1.4 dB (P9 in the figure) and a relatively good axial ratio. It can be seen that the GPS antenna 1B has an axial ratio of about 2.3 dB (P10 in the figure) and has a relatively good axial ratio.

FIG. 8 is a diagram showing the directivity characteristics of the ETC antenna 1A. According to the simulation results shown in FIG. 8, it can be seen that the ETC antenna 1A can obtain a relatively high gain in the range of −30 ° to 150 °.

FIG. 9 is a diagram showing the directivity characteristics of the GPS antenna 1B. According to the simulation results shown in FIG. 9, it can be seen that the GPS antenna 1B can obtain a relatively high gain in the range of −15 ° to 15 °.

In the above description, an example in which the length of the inner main body portion 61 of the GPS antenna 1B is a length corresponding to an arc portion of 270 ° on the outer circumference of the outer main body portion 12 of the ETC antenna 1A has been described. Not limited. As shown in FIG. 10, the length of the inner main body portion 61 of the GPS antenna 1B may be, for example, a length corresponding to an arc portion of 280 ° on the outer circumference of the outer main body portion 12 of the ETC antenna 1A. Further, the length of the inner main body 61 of the GPS antenna 1B may be, for example, as shown in FIG. 11, a length corresponding to a 260 ° arc on the outer circumference of the outer main body 12 of the ETC antenna 1A. good. That is, the length of the inner main body portion 61 of the GPS antenna 1B may be a length corresponding to an arc portion of 260 ° to 280 ° on the outer circumference of the outer main body portion 12 of the ETC antenna 1A. In other words, the length of the inner main body 61 of the GPS antenna 1B may be in the range of 13 / 18L to 14 / 18L, where L is the length of the outer main body 12 of the ETC antenna 1A.

FIG. 12 is a diagram showing VSWR of the antenna unit 100 according to the modified example, in which the vertical axis represents VSWR and the horizontal axis represents frequency (GHz). In FIG. 12, each VSWR in a length corresponding to an arc portion of 260 ° to 280 ° on the outer circumference of the outer main body portion 12 of the ETC antenna 1A is illustrated. There is. According to the simulation results shown in FIG. 12, each VSWR of the ETC antenna 1A is about 1.6 to 1.8 (P11 in the figure), and it can be seen that the power efficiency is relatively good. It can be seen that each VSWR of the GPS antenna 1B is about 1.8 (P12 in the figure), and the power efficiency is relatively good.

FIG. 13 is a diagram showing the gain of the antenna unit 100 according to the modified example, in which the vertical axis represents the gain (dB) and the horizontal axis represents the frequency (GHz). According to the simulation result shown in FIG. 13, the gain of the right-handed circular polarization is about −3.0 dB to −2.0 dB (P13 in the figure), and the ETC antenna 1A receives the right-handed circular polarization satisfactorily. I know I can do it. It can be seen that the GPS antenna 1B has a gain of right-handed circular polarization of about −1.0 dB to 0 dB (P14 in the figure) and can receive right-handed circular polarization satisfactorily.

As described above, the antenna unit 100 according to the embodiment includes the film 2, the ETC antenna 1A, and the GPS antenna 1B. The film 2 is formed in a sheet shape. The outer conductor 10 of the ETC antenna 1A has a length corresponding to one wavelength of the right-handed circular polarization of the ETC, and is formed in an arc shape. The inner conductor 30 of the ETC antenna 1A is provided inside the outer conductor 10 and has a length based on one wavelength of the left-handed circular polarization of the ETC. The inner conductor 30 is formed in an arc shape and suppresses the interference of the left-handed circular polarization of GPS. In the ETC antenna 1A, the feeding point 11R of the outer conductor 10 and the inner end 31R of the inner conductor 30 are connected to each other. The outer conductor 40 of the GPS antenna 1B has a length corresponding to one wavelength of the right-handed circular polarization of the GPS, and is formed in an arc shape. The inner conductor 60 of the GPS antenna 1B is provided inside the outer conductor 40 and has a length based on one wavelength of the left-handed circular polarization of the GPS. The inner conductor 60 is formed in an arc shape and suppresses the interference of the left-handed circular polarization of GPS. In the GPS antenna 1B, the feeding point 41R of the outer conductor 40 and the inner end 61R of the inner conductor 60 are connected to each other. The ETC antenna 1A is provided on the surface 2a of the film 2. The GPS antenna 1B is provided on the back surface 2b of the film 2. The outer conductor 10 of the ETC antenna 1A and the outer conductor 40 of the GPS antenna 1B have a concentric arc shape centered on the central axis. The outer conductor 10 of the ETC antenna 1A and the inner conductor 60 of the GPS antenna 1B have a concentric arc shape centered on the central axis and overlap each other when viewed from the axial direction along the central axis.

With this configuration, the antenna unit 100 arranges the ETC antenna 1A and the GPS antenna 1B on the front and back sides of the film 2 in a state where the ETC right-handed circular polarization and the GPS right-handed circular polarization can be received. Can be done. Therefore, in the antenna unit 100, two antennas can be arranged in the area where one antenna is arranged, so that the increase in size can be suppressed. Further, since the antenna unit 100 forms the ETC antenna 1A and the GPS antenna 1B on the film 2 by pattern printing, the thickness of the antenna unit 100 can be reduced. As a result, the antenna unit 100 can realize the space saving of the space for installing the antenna unit 100.

Further, in the antenna unit 100, since the outer conductor 10 of the ETC antenna 1A and the outer conductor 40 of the GPS antenna 1B are concentric arcs, the distance between the outer conductors 10 and the outer conductors 40 can be made equal. The amount of electrostatic coupling between the arcs can be made equal. As a result, the antenna unit 100 can easily perform impedance management. Further, the antenna unit 100 can suppress a decrease in the level difference between the right-handed circular polarization and the left-handed circular polarization, and can suppress deterioration of the roundness of the circular polarization.

Further, in the antenna unit 100, since the outer conductor 10 of the ETC antenna 1A and the inner conductor 60 of the GPS antenna 1B are concentric arc-shaped and overlap each other, an arc-shaped current distribution is appropriately formed inside the GPS antenna 1B. It is possible to suppress the deterioration of the roundness of the circular polarization. Further, the antenna unit 100 can appropriately form an arc-shaped current distribution on the outside of the ETC antenna 1A, and can suppress deterioration of the roundness of circularly polarized waves.

In the antenna unit 100, the length of the inner conductor 60 of the GPS antenna 1B is in the range of 13 / 18L to 14 / 18L, where L is the length of the outer conductor 10 of the ETC antenna 1A. With this configuration, the antenna unit 100 can suppress the interference between the left-handed circular polarization of ETC and the left-handed circular polarization of GPS, and properly receives the right-handed circular polarization of ETC and the right-handed circular polarization of GPS. can do.

In the antenna unit 100, the inner other end 31L of the inner conductor 30 of the ETC antenna 1A is located inside the outer conductor 10 of the ETC antenna 1A in a disconnected state. Further, the inner other end 61L of the inner conductor 60 of the GPS antenna 1B is located inside the outer conductor 40 of the GPS antenna 1B in a disconnected state. With this configuration, the antenna unit 100 can suppress the interference between the left-handed circular polarization of ETC and the left-handed circular polarization of GPS, and properly receives the right-handed circular polarization of ETC and the right-handed circular polarization of GPS. can do.

In the antenna unit 100, the outer conductor 10 of the ETC antenna 1A has a current flowing between the feeding point 11R and the feeding point 11L of the outer conductor 10. In the inner conductor 30 of the ETC antenna 1A, a current flows between the inner end 31R and the inner other end 31L of the inner conductor 30 in the direction opposite to the outer conductor 10 when viewed from the axial direction. In the outer conductor 40 of the GPS antenna 1B, a current flows between the feeding point 41R and the feeding point 41L of the outer conductor 40. When viewed from the axial direction of the inner conductor 60 of the GPS antenna 1B, a current flows between the inner end 61R and the inner other end 61L of the inner conductor 60 in the direction opposite to the outer conductor 40. With this configuration, the antenna unit 100 can suppress the interference between the left-handed circular polarization of ETC and the left-handed circular polarization of GPS, and properly receives the right-handed circular polarization of ETC and the right-handed circular polarization of GPS. can do.

In the above description, the antenna unit 100 has described an example in which the ETC antenna 1A is provided on the front surface 2a and the GPS antenna 1B is provided on the back surface 2b, but the present invention is not limited thereto. In the antenna unit 100, for example, the GPS antenna 1B may be provided on the front surface 2a and the ETC antenna 1A may be provided on the back surface 2b.

Further, the antenna unit 100 has described an example of receiving radio waves of GPS and ETC, but the present invention is not limited to this, and other radio waves such as satellite broadcasting may be received.

Further, the antenna unit 100 has described an example of receiving the right-handed circular polarization, but the present invention is not limited to this, and the antenna unit 100 may receive the left-handed circular polarization.

2 film (base material)
11L feeding point (the other end of the first outer conductor)
11R Feed point (one end of the first outer conductor)
10 Outer conductor (first outer conductor)
30 Inner conductor (1st inner conductor)
31R Inner end (one end of the first inner conductor)
31L inner other end (the other end of the first inner conductor)
1A ETC antenna (1st antenna)
41L feeding point (the other end of the second outer conductor)
41R Feed point (one end of the second outer conductor)
40 Outer conductor (second outer conductor)
60 Inner conductor (second inner conductor)
61R Inner end (one end of the second inner conductor)
61L inner other end (the other end of the second inner conductor)
1B GPS antenna (second antenna)
2a surface (one side surface)
2b Back side (the other side)
100 antenna unit

Claims (4)

A sheet-shaped base material and
A first outer conductor having a length corresponding to one wavelength of either the first right-handed circular polarization or the first left-handed circular polarization and formed in an arc shape, and provided inside the first outer conductor. The first right-handed circular polarization or the first left-handed circular polarization is formed in an arc shape having a length based on one wavelength of the other, the first right-handed circular polarization or the first left-handed circular polarization. A first antenna configured to include a first inner conductor that suppresses interference of the circular polarization of either one of the waves, to which one end of the first outer conductor and one end of the first inner conductor are connected.
A second outer conductor having a length corresponding to one wavelength of either the second right-handed circular polarization or the second left-handed circular polarization and formed in an arc shape, and provided inside the second outer conductor. The second right-handed circular polarization or the second left-handed circular polarization is formed in an arc shape having a length based on one wavelength of the other, the second right-handed circular polarization or the second left-handed circular polarization. A second antenna configured to include a second inner conductor that suppresses interference of the circular polarization of either one of the waves, to which one end of the second outer conductor and one end of the second inner conductor are connected. Equipped with
The first antenna is provided on one surface of the base material and is provided.
The second antenna is provided on the other side surface of the base material and is provided.
The first outer conductor and the second outer conductor have a concentric arc shape centered on the central axis.
The antenna unit is characterized in that the first outer conductor and the second inner conductor have a concentric arc shape centered on the central axis and overlap each other when viewed from an axial direction along the central axis. The antenna unit according to claim 1, wherein the length of the second inner conductor is in the range of 13 / 18L to 14 / 18L, where L is the length of the first outer conductor. The other end of the first inner conductor is located inside the first outer conductor in a disconnected state.
The antenna unit according to claim 1 or 2, wherein the other end of the second inner conductor is located inside the second outer conductor in a disconnected state. In the first outer conductor, a current flows between one end of the first outer conductor and the other end of the first outer conductor.
In the first inner conductor, a current flows between one end of the first inner conductor and the other end of the first inner conductor in the direction opposite to that of the first outer conductor when viewed from the axial direction.
In the second outer conductor, a current flows between one end of the second outer conductor and the other end of the second outer conductor.
Claim 1 of the second inner conductor, when viewed from the axial direction, a current flows between one end of the second inner conductor and the other end of the second inner conductor in the direction opposite to that of the second outer conductor. The antenna unit according to any one of 3 to 3.

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