JPH0983242A - Small-sized antenna and onboard front end in common use for light beacon and radio wave beacon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized antenna which is adjustable to obtain a desired directivity with a simple configuration. SOLUTION: A plate-shaped inverted F-shape antenna 100 includes a radiation conductor 2 formed on one side of a dielectric board 1 with etching or the like and whose lengthwise size (direction 10 of exciting current) is nearly 1/4 wavelength and a short-circuit conductor plate 4 interconnecting the ground conductor 3 and the radiation conductor 2. A feeding pin 5 is inserted from a rear side of the ground conductor 3 and soldered to a feeding point 6 on the radiation conductor 2. Since the ground conductor 3 is formed obliquely to have an inclined angle 7 so that the distance between the ground conductor 3 and the radiation conductor 2 within a plane orthogonal to the direction 10 of the exciting current is not constant, a desired directivity is obtained by adjusting the inclined angle 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small antenna and a vehicle-mounted antenna for various wireless data communication and mobile communication using quasi-microwave, and more particularly to a small antenna and a vehicle-mounted front end that can obtain desired directivity. .

[0002]

2. Description of the Related Art In recent years, various types of mobile communication and wireless data communication in the quasi-microwave band have been in the limelight. In such a system, a microstrip antenna, an inverted F-type antenna, or the like is often used as a small antenna for a mobile station such as a vehicle or a mobile terminal. FIG. 13 shows a conventional small antenna 2 disclosed in JP-A-59-122202.
FIG. Referring to FIG. 13, a conventional small antenna 200 includes a radiation conductor 2 printed on one surface of a dielectric substrate 1, a ground conductor 3 printed on the other surface, a radiation conductor 2 and a ground conductor 3. Short-circuit pin 11 to connect
, And the inverted F-type antenna 200 is configured with them. The inverted F-type antenna 200 has a stripline 8
Power is supplied by the microstrip line constituted by the ground conductor 3 and the ground conductor 3, and the current in the exciting current direction 10 is excited.

FIG. 14 is a diagram showing a miniaturized inverted F-type antenna 201 disclosed in JP-A-62-34405. Referring to FIG. 14, the inverted F-type antenna 201 includes a radiation conductor 2, a ground conductor 3, a short-circuit plate 4, and a feeding pin 5. By providing the metal protruding portion 19 on the ground conductor 3, the slot width between the ground conductor 3 and the radiation conductor 2 is narrowed to achieve miniaturization.

Further, in recent years, various communication systems have been considered, such as various data communication between a base station and an onboard station using radio waves or light, or communication between onboard stations. Among them, between the infrared beacon device that receives various data transmitted from the roadside antenna to the vehicle with the in-vehicle antenna and the infrared light emitting and receiving element installed on the road and the infrared light emitting and receiving element installed on the vehicle side There are great expectations for the practical application of optical beacon systems that perform various types of data communication.

An outline of such a radio beacon system and an optical beacon system will be described below. FIG.
FIG. 5 is a schematic diagram showing how each beacon of the optical beacon system and the radio beacon system communicates with the vehicle. Referring to FIG. 15, radio beacon 6
1 or the vehicle 63 in which the signal from the optical beacon 62 is traveling
Given to. As is clear from the figure, the radio wave beacon 61 is generally attached at a higher position than the optical beacon 62, and its radio wave arrival area is wide. On the other hand, in the case of the optical beacon 62, the communication area is narrow as shown in the figure.

FIG. 16 is a view in the direction of arrow XVI shown in FIG. Referring to FIG. 16, a radio wave beacon 61 is generally provided on the roadside and covers the entire lanes in one traveling direction. On the other hand, the optical beacon 62 is provided above each lane and communicates with each lane.

Areas having opposite phases are formed on the left and right of the installation location of the radio beacon 61. Therefore, in the receiving vehicle 63, the passage of the radio wave beacon 61 can be detected by detecting this phase inversion, and the traveling direction can be identified by recognizing the phase inversion direction.

Next, a specific example of this radio beacon receiver will be described with reference to FIG. Fig. 17 shows "Development of Beacon Receiver" (Sumitomo Electric, No. 141, pp135-1
40, 1992) is a diagram showing an example of a radio beacon receiver 202 disclosed in FIG. Referring to FIG. 16, the radio beacon receiver 202 includes an on-vehicle antenna 20, a receiving circuit 21, and a coaxial cable 22 for transmitting a signal received by the on-vehicle antenna 20 to the receiving circuit 21. A microstrip antenna using a dielectric substrate can be considered as the vehicle-mounted antenna 20, and the receiving circuit 21 is composed of an electronic circuit such as a bandpass filter, a low noise amplifier, a mixer, and a demodulator.

[0009]

When the above planar antenna is used as a vehicle-mounted antenna, the antenna may be attached to the outside of the vehicle or the inside of the vehicle. When mounting the antenna on the outside of the vehicle, it is necessary to take measures against the appearance of the vehicle and to prevent the effects of wind and rain and theft, resulting in cost increase. For this reason, it is considered better to install the antenna inside the vehicle. On the other hand, even when it is installed in a vehicle, it must be installed so as not to affect the speakers and various instruments. In addition, since the shape of the place where the antenna can be installed differs depending on the vehicle type, there arises a problem that the place where the antenna can be installed is limited, and the selection of the antenna installation place becomes a major problem in manufacturing an in-vehicle antenna.

In order to make effective use of the installation space, for example, it may be possible to mount the vehicle along the surface of the front window or the rear window of the vehicle. When mounted in this manner, in the conventional antenna as shown in FIG. 13, the directivity is such that the main beam is oriented in a direction perpendicular to the inclined surface of the window by mounting it obliquely according to the inclination of the window. It will be. This point will be described with reference to FIGS. 2 (A) and 2 (C).

FIG. 2A shows a conventional inverted F type antenna 200.
It is a figure which shows the state which installed according to the inclination of the window of a vehicle. Both the dielectric substrate 1 and the ground conductor 3 are oriented obliquely according to the inclination of the window, and the radiation conductor 3 is oriented perpendicular to the inclined surface of the window.

FIG. 2C is a diagram showing the directivity of the antenna in such a state, and A shows the directivity of the antenna in the above-mentioned installed state. Here, each of y and z indicates a three-dimensional direction, and the x axis (not shown) indicates a direction perpendicular to the paper surface of FIG. Therefore, the horizontal plane is defined by the xy plane, and the z-axis direction is the vertical direction. FIG.
Referring to (C), when the conventional inverted F-type antenna 201 is obliquely attached, the directivity is inclined, so that the directivity in the horizontal plane is asymmetric. That is, there arises a problem that the gain in the front (or back) direction is large and the gain in the back (or front) direction is small. On the other hand, in general, in the case of mobile communication using such an on-vehicle device, the directivity of the antenna is required to have a low elevation angle gain, which is omnidirectional in the horizontal plane or a gain equal to the front-back direction of the traveling direction. Is desired to be directional.

Therefore, in order to solve such a problem, as a method for tilting the directivity of the antenna, a method of forming an array using two or more elements or a method of loading a non-exciting element on the antenna can be considered. However, there is a problem that the antenna becomes large and the configuration becomes complicated.

When feeding an inverted F-type antenna or a microstrip antenna using a microstrip line, in general, the greater the substrate thickness (distance between the strip line and the ground conductor), the greater the radiation loss due to the microstrip line. Becomes less efficient. Therefore, 2
In the case of a two-layer structure antenna that uses various types of dielectrics and air layers, since the substrate thickness is large, the microstrip line is not used. Conventionally, as shown in FIG. It was supplying power.

As a result, the radiation conductor 2 and the power supply line, the bandpass filter, the low noise amplifier, and the electronic circuit such as the mixer cannot be formed on the same plane. Further, as shown in FIG. 14, when the inverted F-type antenna is downsized, it is necessary to load the ground conductor 3 with the protruding portion, which causes a problem that the configuration of the antenna becomes complicated.

Further, both the optical beacon system and the radio wave beacon system have different service areas, so that they have the following problems. That is, since the optical beacon 62 is installed on a general road and the radio beacon 61 is installed on a highway, both systems must be used together to obtain various road traffic information in a wide area. As a result, it was necessary to prepare in-vehicle receivers for optical beacons and radio beacons.

The present invention has been made to solve the above problems, and has the following objects.

(1) To provide a small antenna that can be adjusted to obtain a desired directivity with a simple structure.

(2) To provide a small directional antenna having a main beam directly above even when the antenna is installed diagonally.

(3) To make it possible to form an electronic circuit on the same substrate as the radiation conductor in the small antenna.

(4) To downsize the antenna as described above with a simple structure. (5) To integrate the radio beacon and the front end of the optical beacon with a simple configuration.

[0022]

A small antenna according to the present invention includes a radiation conductor, a ground conductor facing the radiation conductor, a metal short-circuit plate connecting the radiation conductor and the ground conductor, and a power supply for feeding the radiation conductor. A small antenna provided with a power feeding means, wherein the ground conductor is inclined and opposed to the radiation conductor, whereby the distance between the radiation conductor and the ground conductor is narrowed in order in the first direction, and The direction of the excited current is the second direction intersecting with the first direction.

Since the distance between the radiating conductor and the ground conductor is not constant and changes in a plane orthogonal to the direction of the current excited on the radiating conductor, and is oblique to the ground conductor, the electric field plane is directed. Characteristic (directivity in the plane containing the electric field vector) has a main beam in the direction perpendicular to the radiating conductor surface, and the main beam emits radiation in the magnetic field in-plane directivity (directivity in the plane containing the magnetic field vector). Tilt from the vertical direction of the conductor surface. This allows the main beam to be directed vertically when the antenna is installed diagonally. As a result, it is possible to easily realize a small antenna in which the main beam direction in the magnetic field plane is tilted from the vertical direction of the radiation conductor surface, and even if the antenna is installed diagonally according to the application, the desired direction can be obtained. It is possible to provide a small-sized directional antenna having a beam.

Preferably, the small antenna includes a dielectric substrate, and the radiation conductor is formed on one surface of the dielectric substrate,
A strip line is formed on one surface of the dielectric substrate, and a ground surface is formed on the other surface of the dielectric substrate. The strip line and the ground surface form a microstrip line. The microstrip line is formed so as to extend from the radiation conductor in the first direction, and the ground conductor is formed of a dielectric substrate or a metal plate different from the dielectric substrate and is electrically connected to the ground plane.

By constructing the feed line from the radiating conductor so as to extend in the direction orthogonal to the exciting current and in the direction in which the distance between the radiating conductor and the grounding conductor becomes smaller, symmetry of electric field plane directivity is maintained and low loss is achieved. The feed line can be formed on the same dielectric substrate as the radiation conductor, and a low profile antenna can be realized. Further, electronic circuit parts such as a bandpass filter, a low noise amplifier and a mixer can be formed on the same substrate, and a low profile receiver can be realized.

More preferably, the radiation conductor is zigzag-shaped in the direction of the current excited on the radiation conductor.

By adopting such a structure, the antenna length can be made shorter than a quarter wavelength with a simple structure, and the antenna can be downsized with a simple structure.

[0028] In another aspect of the present invention, a radio wave beacon system in which various data transmitted from a roadside antenna to a vehicle is received by a vehicle-mounted antenna, and an infrared ray emitting / receiving element installed on a road and a vehicle-side infrared ray In an optical beacon system that transmits and receives various data between light emitting and receiving elements, any one of the above small antennas is used as a radio wave beacon receiving antenna. The receiving antenna and at least one of the light receiving element or the light emitting element for the optical beacon vehicle are provided on the same dielectric substrate, and the dielectric substrate is obliquely attached so as to have an inclination angle in the traveling direction.

Since at least one of the optical beacon light receiving element and the light emitting element mounting board and the radio wave beacon receiving antenna using any of the above small antennas are formed on the same board, a low profile and compact radio wave, An optical beacon shared antenna can be provided.

Since the antenna for both light and radio beacons is obliquely installed so as to have an inclination angle in the traveling direction, the light-receiving element or the light-emitting element has sensitivity in the direction in which the vertical direction is inclined, so that the roadside light in front of the vehicle is detected. Communication with the beacon station can be performed efficiently. Moreover, since the main beam of the radio wave beacon receiving antenna is directed in the vertical direction and symmetrical directivity in the front-back direction of the traveling direction is obtained, communication with the roadside radio wave beacon station can be efficiently performed. In addition, the control circuit for the radio beacon and the control circuit for the optical beacon can be shared, and the circuit area can be reduced.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION

(1) First Embodiment Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a plate-shaped inverted F according to a first embodiment of the present invention.
It is a figure which shows the whole structure of the type | mold antenna 100.

In the figure, (A) is a diagram showing the overall configuration of the plate-shaped inverted F-type antenna, and (B) shows the three-dimensional axial directions of the plate-shaped inverted F-type antenna 100 shown in (A). It is a figure. Referring to FIG. 1, a plate-shaped inverted F-type antenna 100 has a dielectric substrate 1, a radiation conductor 2 provided on the dielectric substrate 1, and an inclination angle 7 with respect to the dielectric substrate 1. It includes a ground conductor 3 provided to face each other, and a conductor short-circuit plate 4 connecting the ground conductor 3 and the radiation conductor 2. The radiation conductor 2 is formed by etching or the like on one surface of the dielectric substrate 1 so that the longitudinal direction (excitation current direction 10) has a wavelength of about ¼.

The feeding pin 5 is passed from the rear surface of the ground conductor 3 and is connected by soldering at the feeding point 6 on the radiation conductor 2. As the power feeding pin 5, a center conductor of a power feeding coaxial cable (not shown) or the like is used. The short-circuit plate 4 is connected to the radiation conductor 2 by soldering or the like through a slit hole 26 provided in the dielectric substrate 1, and the other end thereof is connected to the ground conductor 3. The feeding point 6 is provided on the radiating conductor 2 at a position slightly apart from the short-circuit plate 4 and is matched with the feeding system. At this time, a current flowing from the short-circuited end 27 side to the open end 28 side is excited on the radiation conductor 2, and the length of the radiation conductor 2 in the longitudinal direction is about a quarter wavelength of the used wavelength, which is desirable. It resonates at a frequency and operates as an antenna.

The ground conductor 3 has a constant distance between the ground conductor 3 and the radiation conductor 2 in a plane orthogonal to the exciting current direction 10 and is obliquely intersected with the radiation conductor 2 so as to have an inclination angle 7. ing. Therefore, the direction of the magnetic current considered between the edge of the radiating conductor 2 on the side of the open end 28 and the ground conductor 3 is not parallel to the surface of the radiating conductor 2 but parallel to the surface of the radiating conductor 2 and the surface of the grounding conductor 3. It is thought that the direction will be tilted in any direction.

The directivity in the plane including the excitation current direction 10 (xz plane in FIG. 1B) is the electric field plane directivity, and the plane orthogonal to the current direction 10 (yz plane in FIG. 1). The directionality inside the parenthesis is the magnetic field directionality. Due to the inclination of the radiation conductor 2 and the ground conductor 3, the electric field plane (xz plane) directivity is not affected by the inclination of the radiation conductor 2 and the ground conductor 3 and has a main beam in the vertical direction of the radiation conductor 2. In the interface (yz plane) directivity, the main beam direction shifts due to the inclination of the magnetic current described above. As a result, a directivity inclined from the vertical direction of the radiation conductor 2 to the vertical direction of the ground conductor 3 is obtained. In this embodiment, the main beam direction can be tilted with a very small antenna, and the beam shift amount can be controlled by changing the tilt angle 7.

Next, specific effects of the antenna according to the present invention will be described. FIG. 2B is a diagram showing an installation state of the inverted F-type antenna 100 shown in FIG. 1, and FIG. 2C shows the directivity of the inverted F-type antenna 100 installed as shown in FIG. 2B. It is a figure which shows (B in FIG.2 (C)). With reference to FIG. 2 (C), a directivity symmetrical with respect to the z-axis direction can be obtained even though the radiation conductor 3 is inclined. In the figure, A is the directivity of the conventional inverted F-type antenna shown in FIG. 2A. By comparing this B with A, the angle of the ground conductor 3 in FIG. A desired directivity can be obtained by inclining to.

Next, an example of using this antenna will be described. Since the antenna according to this embodiment can obtain the desired directivity as described above, the following application examples are possible. That is, by mounting this antenna in such a manner that the radiation conductor surface is aligned with the window surface of the automobile, it is possible to obtain good directivity in which the main beam is in the vertical direction even though the window is inclined. .
As another example of use, the antenna according to the present invention is mounted in a form such as being embedded in a ceiling or a wall in an indoor wireless data transmission system or the like. Although it has a low profile and flat structure in appearance, it is possible to incline the main beam direction and direct it to a desired direction. Also,
A high-gain beam tilt array antenna can be configured by arraying this antenna.

The position of the radiation conductor 2 is not the center of the dielectric substrate 1 but the position shown by the broken line in FIG. 1 (radiation conductor 1
As shown in 4), by displacing in the direction orthogonal to the excitation current direction 10 and installing it on the end of the dielectric substrate 1, the main beam direction can be further tilted by utilizing diffraction, or conversely by the main beam by diffraction. It is also possible that the shift is canceled by the beam shift due to the inclination angle 7.
The width of the short-circuit plate 4 may be smaller than the width of the radiation conductor 2, and for example, one or a plurality of power supply pins 5 may be used instead. In the case of this embodiment, the dielectric substrate 1 is provided between the radiation conductor 2 and the ground conductor 3.
It has a two-layer structure of dielectric and air. Therefore,
Since the loss due to the dielectric loss tangent of the dielectric substrate can be suppressed to a low level, highly efficient characteristics can be obtained even if an inexpensive dielectric substrate such as a glass epoxy substrate is used.

Instead of the two-layer structure as described above, for example, the dielectric substrate 1 may have a one-layer structure of a dielectric having a triangular prism structure so as to enter the space between the radiation conductor 2 and the ground conductor 3. This example is shown in FIG. Further, by providing the radiation conductor 2 on the back surface of the dielectric substrate 1, a single layer structure of an air layer can be obtained. Further, the ground conductor 3 does not have to be a flat surface, and may have, for example, a stepped shape (see FIG. 4). The antenna according to the present invention has a short-circuit plate 4
The length of the radiation conductor 2 in the longitudinal direction is about 2 of the used wavelength.
The same effect can be obtained even with a patch antenna configuration having one-half wavelength.

(2) Second Embodiment FIG. 5 is a diagram showing the overall configuration of a plate-shaped inverted F-type antenna 101 according to the second embodiment of the present invention. The second embodiment is different from the first embodiment in that the strip line 8 is provided, but since the other parts are basically the same, the same parts are designated by the same reference numerals. Is attached and the description thereof is omitted.

Referring to FIG. 5, a plate-shaped inverted F-type antenna 10 is provided.
1 has a length in the longitudinal direction of about 4 as in the first embodiment.
It includes a radiation conductor 2 having a wavelength of one-half, a ground conductor 3, and a short-circuit plate 4. Electric power is fed at a feeding point 6 by a microstrip line constituted by a strip line 8 printed on the front surface of the dielectric substrate 1 and a conductor ground surface 9 printed on the back surface. The ground plane 9 is electrically connected to the ground conductor 3 by soldering or the like. Further, in order not to affect the antenna characteristics, it is necessary that the radiation conductor 2 and the ground plane 9 do not overlap. On the other hand, in order for the stripline 8 to operate as a microstrip line, it is preferable that the ground plane 9 extends to the edge of the radiation conductor 2. Therefore, it is desirable that the distance between both edges of the ground plane 9 and the radiation conductor 3 be about 1 to 3 mm.

It is preferable that the microstrip line extends in a direction orthogonal to the exciting current direction on the radiation conductor 2 in order to maintain the symmetry of the electric field plane directivity. By extending in a direction in which the distance between the radiation conductor 2 and the ground conductor 3 decreases, the ground plane 9 and the ground conductor 3 can be easily connected. Further, in the method of the conventional example (FIG. 13) in which the microstrip line is extended in the excitation current direction, the width of the radiation conductor 2 is required to be at least the width of the strip line 8 or more. However, in the configuration as in the second embodiment, the width of the radiation conductor 2 can be made narrower than the width of the strip line 8.

With the above structure, the microstrip line is formed on the same dielectric substrate as that of the radiation conductor 2, so that coplanar power feeding can be realized without increasing the line width and suppressing the reduction in efficiency due to radiation loss. To be done. As shown in FIG. 5, since the electronic circuit 24 composed of a bandpass filter, a low noise amplifier, a mixer and the like can be formed at the end of the microstrip line on the same dielectric substrate 1 on the side opposite to the antenna side, the feed line is formed. It is possible to reduce the loss due to the routing, and to realize a highly efficient and low-profile receiver.

(3) Third Embodiment FIG. 6 is a diagram showing a third embodiment of the present invention. Referring to FIG. 6, a plate-shaped inverted F-type antenna 1 according to the second embodiment.
The radiation conductor 2 and the strip line 8 in 01 are configured on the back surface of the dielectric substrate 1, and the ground plane 9 is configured on the front surface of the dielectric substrate 1, respectively.
2 is used to connect the radiation conductor 2 and the ground conductor 3.

The through-hole pin 12 is electrically connected to the ground conductor 3 at one end, and is electrically connected to the radiation conductor 2 at the other end through the through-hole plating 17 provided on the dielectric substrate 1. The ground conductor 3 and the ground plane 9 are connected by soldering or the like via the through-hole plating 17. The strip line 8 is a circular cutout 1 provided in the ground conductor 3.
3 and extends toward the substrate end.

Plate-shaped inverted F-type antenna 1 according to the third embodiment
In 02, as in the case of the second embodiment, by mounting the electronic circuit 24 on the end of the microstrip line on the side opposite to the antenna side, each electronic circuit component is mounted on the back surface of the dielectric substrate 1. Therefore, the surface side can be made flat. Further, since the ground conductor 3 and the ground plane 9 serve as a shield for the electronic circuit 24, it is possible to eliminate the adverse effect of unnecessary radiation from the electronic circuit 24 on the antenna.

(4) Fourth Embodiment FIG. 7 is a diagram showing the overall configuration of an inverted F type antenna 103 according to a fourth embodiment of the present invention. It is configured in a zigzag shape toward 10. Usually, the radiation conductor of the inverted F-type antenna needs to have a length in the excitation current direction 10 of about ¼ wavelength. However, with the configuration of this embodiment, the length can be made shorter than a quarter wavelength. In the conventional example of downsizing the inverted F-type antenna, FIG.
As shown in FIG. 4, it is necessary to load the metal protrusion 19 on the ground conductor 3, so that the configuration is complicated. However, the plate-shaped inverted F-type antenna 10 according to this embodiment is
In No. 2, downsizing can be achieved with a simple configuration in which only the radiation conductor pattern is changed. Moreover, the directivity equivalent to that of the first to third embodiments can be obtained.

(5) Fifth Embodiment FIG. 8 is an overall configuration diagram showing a fifth embodiment of a plate-shaped inverted F-type antenna according to the present invention. In the fifth embodiment,
The above small antenna is applied as a front end for both radio waves and optical beacons. FIG. 9 is a view of the front end 31 shown in FIG. 8 as viewed from the back side.

Referring to FIG. 9, the front end 31 is
The light receiving element 15 for optical beacon and the light emitting element 16 for optical beacon are mounted on the front surface side of the dielectric substrate 1, the radiation conductor 2 and the strip line 8 are formed on the back surface side by etching, and the metal plate 30 is attached. There is.

FIG. 10 is a detailed view of the metal plate 30. FIG.
Referring to 0, in the metal plate 30, the ground conductor 3, the triangular short-circuit plate 4 and the substrate support portion 34 are integrally formed by sheet metal working, and the short-circuit plate 4 and the substrate support portion 34 have the protrusions 29, respectively. It is provided.

With reference to FIGS. 8 to 10, the protrusions 29 of the metal plate 30 are fitted into the through holes plated slits 26 from the back surface of the dielectric substrate 1, and solder is applied to the front surface of the dielectric substrate 1. It is connected by attachment. One side of the ground conductor 3 is electrically connected to the ground plane 9 through the through hole plating 11. The substrate support portion 34 has the same shape as the short-circuit plate 4, and is provided to support the dielectric substrate 1 at a constant angle. By using the integrally formed metal plate 30, it is possible to easily connect and fix the ground conductor 3 and the dielectric substrate 1. Further, the inclination angle 7 of the ground conductor 3 with respect to the radiation conductor 2 can be determined by the angle between the side of the short-circuit plate 4 and the side of the substrate support 34 on the protrusion 29 side and the side on the ground conductor 3 side.
The desired inclination angle 7 can be accurately and easily realized.

The plate-shaped inverted F-type antenna 104 composed of the radiation conductor 2, the short-circuit plate 4 and the ground conductor 3 operates as a radio wave beacon receiving antenna, and the ground surface 9 printed on the front surface of the dielectric substrate 1 and the back surface thereof. Power is supplied by the microstrip line formed by the printed stripline 8.

The signal transmitted from the roadside radio beacon station is received by the receiving antenna, and the received signal is guided to the electronic circuit 24 composed of a low noise amplifier, a bandpass filter, a mixer and the like through the strip line 8. A signal frequency-converted to an intermediate frequency by the electronic circuit 24 is input to a demodulation circuit (not shown) via the coaxial cable 22 to demodulate information, and various information is displayed on a monitor (not shown) or the like.

The electronic circuit 24 can be mounted on either the front surface or the back surface of the dielectric substrate 1. However, since the electronic circuit 24 is a high-frequency circuit in which high-profile components such as a bandpass filter are mounted, it has a high profile. Shield plate is required. In order to suppress the adverse effect of this shield plate on the antenna,
It is more desirable that it is formed on the back surface of the dielectric substrate 1. Further, the demodulation circuit may be formed on the front surface or the back surface of the dielectric substrate 1 similarly to the electronic circuit 24. On the other hand, a photodiode or the like is used as the optical beacon light receiving element 15, and an infrared light emitting diode or the like is used as the light emitting element 16. The signal transmitted from the optical beacon 62 is received by the light receiving element 1
5, the received signal is amplified by the electronic circuit 25 including a preamplifier circuit and the like.

Next, a vehicle-mounted beacon receiving / transmitting device 64 to which the small antenna according to the present invention is applied will be described. FIG. 11 is a block diagram showing the main part of the in-vehicle beacon receiving / transmitting device 64. With reference to FIG. 11, a vehicle-mounted beacon receiving / transmitting device 64 includes a radio wave beacon processing circuit 65 that processes a signal transmitted from a roadside radio wave beacon 61,
An optical beacon processing circuit 66 for transmitting and receiving the optical beacon 62 is included. The radio wave beacon processing circuit 65 includes the receiving antenna 105, the electronic circuit 24, and a signal whose frequency is converted to an intermediate frequency by the electronic circuit 24.
The data display unit 44 includes the data demodulation unit 42 and the data processing unit 43 that processes the demodulated data. Electronic circuit 24
Includes a power amplification unit 40 that amplifies a reception signal received by the reception antenna 105, and a frequency conversion unit 41 that frequency-converts the amplified signal into an intermediate frequency.

The optical beacon processing circuit 66 receives the signal transmitted from the roadside optical beacon 62.
An amplifier 45 that amplifies the received signal, a demodulator 46 that demodulates the amplified signal, a data processor 48 that processes the demodulated signal, and a data processed by the data processor 48. A light emission driver unit 47 for outputting to the optical beacon station 62 via the element 16. The amplifier 45, the demodulator 46, and the light emission driver 47 constitute the electronic circuit 25. The data processed by the data processing unit 48 is displayed on the data display unit 44.

Since the radiation conductor 2, the light receiving element 15 and the light emitting element 16 are formed on the same substrate in the front end 31 for both radio wave and optical beacon according to the fifth embodiment, the demodulation circuit and the preamplifier circuit are provided. Also, a part of the data processing circuit or the like can be integrally formed on the front surface or the back surface of the dielectric substrate 1. Alternatively, it is possible to use a multilayer substrate instead of the dielectric substrate 1 and configure a circuit group over a plurality of layers.

Control circuits for radio beacons and optical beacons inside the electronic circuits 24 and 25 can be shared, and the circuit area of the front end 31 can be reduced. Further, by using the antennas of the first to third embodiments as the receiving antenna 105, it is possible to reduce the loss due to the dielectric as shown in the first embodiment. Therefore, the dielectric substrate 1 is made of glass epoxy. An inexpensive substrate such as a substrate can be used.
As a result, a highly efficient antenna and receiver can be realized at low cost.

Next, a specific example of using the front end 31 shown in FIG. 9 will be described. FIG. 12 shows a mounting angle (for example, 45 °) in which the front end 31 for both radio wave and light beacon is inclined along the inside of the windshield 33 of the vehicle 63 on the dashboard 36 in the traveling direction.
FIG. 6 is a schematic diagram showing a state in which the receiving antenna is attached so as to be located on the upper side. FIG. 12B shows the front end 31.
12C is an enlarged view of FIG. 12C, and is a cross-sectional view of a portion indicated by an arrow C-C in FIG. 12B.

In the optical beacon system, as shown in FIG. 15, the elevation angle when the optical beacon 62 is viewed from the vehicle 63 is 40 degrees.
Communication is performed when the angle is between 60 ° and 60 °. Infrared rays emitted from the light emitting element 16 are emitted in a direction normal to the surface of the dielectric substrate 1. Therefore, when the dielectric substrate 1 in the front end 31 is installed obliquely with respect to a horizontal plane, the infrared rays are vertically reflected. It is irradiated in a direction inclined from the direction. Also, the light receiving element 1
The same applies to 5 as well, and has a strong sensitivity in a direction inclined from the vertical direction. As a result, the optical beacon 6 in front of the vehicle 63
2 can be efficiently communicated with.

On the other hand, the receiving antenna 105 has an oblique structure in which the ground conductor 3 has an inclination angle 7 with respect to the radiating conductor 2, as shown in each of the above-described embodiments,
The main beam direction is from the direction perpendicular to the surface of the radiation conductor 2 to the ground conductor 3
Shift in the vertical direction of the plane. An appropriate angle (for example, 45 °) by adjusting the inclination angle 7 to the mounting angle of the front end 31.
By setting to, the ground conductor 3 can be configured to be parallel to the horizontal plane. As a result, directivity in which the main beam is directed in the vertical direction, that is, symmetrical directivity in the front-back direction of the traveling direction is obtained.

Since the receiving antenna is located above the light receiving element and the light emitting elements 15 and 16 for the optical beacon station, its directivity is not easily influenced by the light receiving and emitting elements 15 and 16, so that good directivity can be maintained. . As a result, good communication characteristics with the radio beacon 61 can be obtained.

Further, the position of the receiving antenna 105 in the front end 31 in the lateral direction (excitation power direction 10) affects the electric field plane directivity (in-plane directivity in the road crossing direction in FIG. 12). In order for the directivity to have the main beam in the vertical direction and be symmetrical in the left-right direction, the position of the radiation conductor 2 in the lateral direction is set to the front end 31.
It is desirable to be near the center of.

[Brief description of drawings]

FIG. 1 is a diagram showing an overall configuration of a plate-shaped inverted F-type antenna according to the present invention.

FIG. 2 is a diagram showing an effect of a plate-shaped inverted F-type antenna according to the present invention.

FIG. 3 is a view showing a modification of the plate-shaped inverted F-type antenna according to the present invention.

FIG. 4 is a diagram showing a modification of the plate-shaped inverted F-type antenna according to the present invention.

FIG. 5 is a view showing another embodiment of the plate-shaped inverted F-type antenna according to the present invention.

FIG. 6 is a view showing still another embodiment of the plate-shaped inverted F type antenna according to the present invention.

FIG. 7 is a view showing still another embodiment of the plate-shaped inverted F-type antenna according to the present invention.

FIG. 8 is a diagram showing a configuration when the plate-shaped inverted F-type antenna according to the present invention is used as a reception antenna of a radio beacon and a front end for both optical beacons.

FIG. 9 is an overall view showing a state in which the plate-shaped inverted F-type antenna according to the present invention is applied as a reception antenna for a radio beacon and a front end for both optical beacons.

FIG. 10 is a diagram showing a metal plate for mounting the front end.

FIG. 11 is a block diagram showing a configuration of a vehicle-mounted beacon receiving / transmitting device.

FIG. 12 is a diagram showing a specific usage state of the front end.

FIG. 13 is a diagram showing a conventional inverted F-type antenna.

FIG. 14 is a diagram showing a conventional inverted F-type antenna.

FIG. 15 is a schematic diagram showing an outline of a beacon system.

FIG. 16 is a schematic diagram showing an outline of a beacon system.

FIG. 17 is a diagram showing a conventional radio beacon receiver.

[Explanation of symbols]

 1 Dielectric Substrate 2 Radiating Conductor 3 Grounding Conductor 4 Short-Circuiting Board 5 Feeding Pin 6 Feeding Point 7 Tilt Angle 8 Stripline 9 Grounding Surface 10 Excitation Current Direction 11 Short-Circulating Pin 12 Notch 14 Radiating Conductor 15 Photosensitive Element 16 Light emitting element 17 Through hole plating

Claims (4)

[Claims] 1. A radiation conductor, a grounding conductor facing the radiation conductor, a conductor short-circuit plate connecting the radiation conductor and the grounding conductor, and a power feeding means for feeding power to the radiation conductor. A small antenna, wherein the ground conductor is inclined and opposed to the radiating conductor, whereby the distance between the radiating conductor and the ground conductor is gradually narrowed in the first direction, and the radiating conductor is excited on the radiating conductor. The small antenna in which the generated electric current flows in a second direction intersecting with the first direction. 2. The small antenna includes a dielectric substrate, the radiation conductor is formed on one surface of the dielectric substrate, and a strip line is formed on the one surface of the dielectric substrate. A ground plane is formed on the other surface of the dielectric substrate, and a microstrip line is formed by the strip line and the ground plane, and the microstrip line is formed on the radiation conductor in the first direction. The small antenna according to claim 1, wherein the ground conductor is formed of a dielectric substrate or a metal plate different from the dielectric substrate and is electrically connected to the ground plane. 3. The small antenna according to claim 1, wherein the radiation conductor is formed in a zigzag shape in the second direction. 4. An on-vehicle front end for both an optical beacon and a radio wave beacon for a vehicle information communication system using an optical beacon and a radio wave beacon provided on the roadside, which receives an optical signal for communicating the optical beacon with the vehicle information. Means, an optical signal emitting means, and an electric wave signal receiving means for receiving information from the electric wave beacon, wherein the small antenna according to claim 1, 2 or 3 is used as the electric wave signal receiving means, At least one of the signal receiving unit and the optical signal emitting unit is provided on the dielectric substrate of the small antenna, and the dielectric substrate is installed so as to be inclined with respect to the traveling direction of the vehicle. In-vehicle front end for shared beacons.