JPH09246827A - Vehicle antenna system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To incorporate a TV antenna and a GPS antenna into a door mirror. SOLUTION: A TV antenna element 2 is made up of a 1st antenna strip element 4 and a 2nd antenna linear element 5 and adhered to an inner face of a door mirror cover 1 as a loop. The characteristic is improved through the combination of a capacitance of the 1st antenna element 4 and an inductance of the 2nd antenna element 5. Furthermore, since the antenna is connected to a car body via the 2nd antenna linear element 5, wiring is facilitated. Moreover, a GPS assembly is arranged at the rear side of the mirror.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle antenna device in which an antenna element is incorporated in a vehicle door mirror.

[0002]

2. Description of the Related Art Conventionally, a vehicle has a radio tuner and a television tuner. Also, car phones,
An increasing number of devices are equipped with data processing terminals and GPS devices for navigation systems.

In order to use such a device in a vehicle, it is necessary to receive radio waves, which requires an antenna. Here, it is easier to secure the performance of the antenna when the field of view is as wide as possible, and it is preferable that the antenna is provided so as to protrude from the vehicle body from the viewpoint of performance alone. However, the antenna protruding from the vehicle body has problems in design and wind noise during traveling, and from this aspect, it is desired that the antenna does not protrude from the vehicle body as much as possible.

As the antenna which does not protrude from the vehicle body, a glass antenna formed as a pattern on the rear glass is used, but there is a problem that it is easily affected by variations in the relative permittivity of the window glass and production control is difficult. . In addition, if many antenna patterns are arranged, there is a problem that the visibility deteriorates accordingly.

As an arrangement location of such an antenna, the interior of a room mirror, a side mirror (door mirror), or the like can be considered. Placing the antenna in such a place can completely eliminate the problem of appearance. Therefore, JP-A-63-
In Japanese Patent No. 170349, one in which an antenna is arranged inside a room mirror, a side mirror, or the like is proposed.

[0006]

When the antenna is arranged inside the door mirror, its size must be considerably small. However, in order to reduce the size of the TV antenna, it is preferable to make the antenna into a band shape rather than a linear shape. However, the door mirror is usually a retractable type, and when the antenna is stored like a strip,
It is considered difficult to maintain its shape.

Further, it is considered that the GPS antenna is relatively easy to miniaturize the antenna element itself and can be physically (dimensionally) accommodated in the door mirror. However, if the size of the antenna element is reduced, it is highly possible that the receiving performance is significantly deteriorated due to the installation condition (environment), and the manufacturing yield is expected to deteriorate. Therefore, there has been no proposal up to now to accommodate the GPS antenna in the door mirror. Also,
The GPS antenna needs to be less susceptible to the influence of reflected waves from the road surface or the like.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an antenna device suitable for incorporation in a door mirror.

[0009]

According to the present invention, in an apparatus in which an antenna element is installed in a vehicle door mirror case, the antenna element is a strip-shaped first antenna element,
A linear second antenna element serially coupled to the first antenna element, the band surface of the first antenna element is fixed to an inner surface of a door mirror case, and the second antenna element is attached to a vehicle mounting side of the door mirror. It is characterized by being arranged.

The TV broadcast wave is received by the first antenna element. This first antenna element is band-shaped and can preferably receive wideband TV radio waves. Also, the first
When the antenna element is shortened with respect to the center frequency of the received radio wave, the first antenna element exhibits the capacitive property, but the second antenna element exhibits the inductance property, and the reactances of the two antenna elements are offset to each other, thereby making a suitable antenna. . Further, the mirror acts as a parasitic antenna element, and wide band reception can be effectively performed.

Further, since the second antenna is arranged on the vehicle mounting side, the connection with the vehicle side becomes easy even if there is a mechanism for storing and rotating the door mirror.

Another aspect of the present invention is a device in which an antenna element is installed in a door mirror case of a vehicle, wherein the antenna element is a GPS antenna, and the GPS antenna is arranged behind a mirror surface so as to face upward. To do.

Since the door mirror projects from the vehicle, the field of view of the satellite is relatively good, and the radio waves from the satellite can be effectively received.

Further, since the GPS antenna is arranged behind the mirror, there is little mixing of reflected waves from the building or the road surface,
Accurate position detection can be performed by reducing erroneous detection.

In still another aspect of the invention, an electrically conductive actuator for changing the angle of the mirror surface is provided, and the G
The PS antenna is on the vehicle front side of the mirror surface,
It is characterized in that it is arranged inside or on the upper side in the vehicle width direction of the conductive actuator. With this arrangement, reception of reflected waves can be prevented even by the electrically conductive actuator.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention (hereinafter referred to as embodiments) will be described below with reference to the drawings.

[First Embodiment] FIG. 1 is a view showing the arrangement of a vehicle antenna device according to the first embodiment. An antenna element (TV antenna element 2) is housed inside a door mirror cover 1. It The TV antenna element 2 is connected to the coaxial cable 3 for power supply, receives power from here, and receives TV radio waves.

Then, the TV antenna element 2 is used.
Is composed of a strip-shaped first antenna element 4 and a second antenna element 5 made of a linear conductor.
One end of the antenna element 5 is connected to the center conductor of the coaxial cable 3, and the other end is connected to the first antenna element 4
Is connected to one end. The other end of the first antenna element 4 is an open end. The outer conductor of the coaxial cable 3 is electrically connected to the vehicle body and grounded.
For example, the inner conductor may be introduced into the door mirror cover 1 by grounding it near the pillar to which the door mirror is attached, but the coaxial cable 3 is extended into the door mirror cover 1, and the door mirror cover 1 is rotated with respect to the vehicle body. It may be grounded to the vehicle body via a metal shaft that is freely supported. The mirror 6 is provided on the front side of the door mirror cover 1.

The first antenna element 4 is composed of a strip-shaped conductor, for example, a conductive tape made of copper foil.
It has a width of -30 mm and a length of 200-300 mm. On the other hand, the second antenna element 5 has a diameter of 1 mm.
It is a copper wire having a length of about 50 mm.
Then, these first and second antenna elements 4, 5
Is attached to the inner surface of the door mirror cover 1. That is, the first antenna element 4 is attached to the inner surfaces of the upper and right sides (the side farther from the vehicle body) of the door mirror cover 1, and the second antenna element 5 is the inner surface of the left side (the side closer to the vehicle body) of the door mirror cover 1. Attached to. The door mirror cover 1 is made of a plastic material.

The TV broadcast wave is received by such a TV antenna element 2, but the TV broadcast wave is first received by the first antenna element 4. The first antenna element 4 has a strip shape and has many current paths. Therefore, it is possible to receive a wide band radio wave necessary for receiving the TV broadcast wave.

Further, the first antenna element 4 is
The length is shorter than the length required to receive radio waves in the TV band. Therefore, the impedance of the first antenna element 4 is capacitive. On the other hand, the first antenna element 4 has a linear second antenna element 5
But is connected. This second antenna element 5
Since is linear, its impedance exhibits inductance.

As described above, the TV antenna element 2 of this embodiment is configured by connecting the capacitive first antenna element 4 and the inductance second antenna element 5. Therefore, by adjusting the capacitive and inductive reactances of the two, the total impedance of the two can be made such that their reactances are offset. By this, the matching condition can be satisfied, and good reception power can be supplied to the TV receiver connected to the other end of the coaxial cable 3.

Furthermore, this TV antenna element 2
The loop formed by is shaped so as to surround the mirror 6. The reflection film of the mirror 6 is formed of a conductor (for example, a vapor deposition film of aluminum). Therefore, the TV antenna element 2 has a structure in which the parasitic element is loaded. Therefore, by using this mirror, the frequency characteristics of the TV antenna element 2 can be made wider. Therefore, T
The requirement for the accuracy of the V antenna element 2 is not strict, the manufacturing yield is improved, and the cost is reduced.

Since the second antenna element 5 is linear, the cable (wire harness) from the inside of the door mirror cover 1 to the vehicle side can be easily routed, and the workability of assembly can be improved. .

Although the second antenna element 5 is extended to the outside of the door mirror cover 1 in the above configuration, the coaxial cable 3 is guided to the inside of the door mirror cover 1 and provided on the rotating shaft portion of the door mirror cover 1. The outer conductor of the coaxial cable 3 may be grounded to the metal part (which is electrically connected to the vehicle body). Further, the second antenna element 5 may be arranged in a meandering manner.

[Second Embodiment] FIG. 2 shows a vehicle antenna device according to a second embodiment. In the first embodiment described above,
The TV antenna element 2 has been described.
In the embodiment, the GPS antenna assembly 7 is included. That is, as shown in FIG. 2, a mirror 6 is provided on the front side inside the door mirror cover 1, and a GPS antenna assembly 7 is arranged behind the mirror 6. Further, the mirror 6 is an electric mirror actuator 8
This mirror electric actuator 8
By this, the direction of the mirror 6 is changed back and forth and left and right. In the usual case, as shown in FIG. 3, one point on the back of the mirror 6 is pivotally supported by the electric mirror actuator 8 as the reference point 8a, and the left-right direction drive shaft 8b that can move forward and backward to the side of the reference point 8a, and A front-rear direction drive shaft 8c that is freely movable back and forth is provided above (or below). Therefore, the mirror 6 rotates in the horizontal plane by moving the left-right direction drive shaft 8b forward and backward, and the mirror 6 rotates in the elevation direction by moving the front-back direction drive shaft 8c forward and backward.

A GPS antenna assembly 7 is arranged on the back of the electric actuator 8 for the mirror on the vehicle body side.

FIG. 4 is a diagram showing the structure of the antenna element 10 housed in the GPS antenna assembly 7. As described above, the present antenna element 10 is composed of the microstrip antenna in which the square antenna patch 12 smaller than the dielectric substrate is formed on the surface of the square dielectric substrate 11. In this example, one side of the dielectric substrate 11 is 25 mm, the thickness is 4 mm, and a ceramic substrate having a dielectric constant of about 21 is adopted. The dielectric constant is preferably about 20-40. Further, the antenna patch 12 is formed by using a printed and baked film of copper with one side (L) of about 20 mm.

Further, in the present embodiment, the feeding to the antenna patch 12 is two-point feeding. That is, as shown in FIG. 4, feeding points fp1 and fp2 are provided at positions different from each other by 90 ° when viewed from the center of the antenna patch 12, respectively. This ensures that the antenna element can be excited with circular polarization.

That is, by providing a cut or a protrusion around the antenna patch 12 in the case of single-point feeding,
Achieve excitation with a given circular polarization. Therefore, the axial ratio of circularly polarized waves changes greatly depending on the frequency.

On the other hand, if the two-point power feed is used as in the present embodiment, the circularly polarized wave is generated according to the phase of the current fed to the two points.
Since it is excited, a suitable axial ratio can be secured in a wide band. The desired characteristics can be obtained by adjusting the distance from the center of each feeding point fp1 and fp2 and the size (L × L) of the antenna patch 12.

FIG. 5 shows the relationship between the axial ratio and the frequency of the one-point feeding and the two-point feeding. Thus, in the case of single-point power feeding, a very good axial ratio is obtained at the center frequency, but when the frequency deviates from the central frequency, the axial ratio becomes extremely poor. On the other hand, in the case of the two-point feeding, it is understood that a stable and good axial ratio can be obtained in a wide range, and the excitation by suitable circular polarization can be performed in a wide range.

In the microstrip antenna as in the present embodiment, the entire reception (resonance) band (frequency range in which the standing wave ratio (SWR) is 2 or less) of the antenna is
It is possible to make the axial ratio low (good). You can make full use of the performance of the antenna.

On the other hand, in the case of the one-point feeding system, the band with a good axial ratio is about 20 to 30% of the resonance band of the antenna.

FIG. 6 shows the overall structure of the GPS antenna assembly 7. In this way, the antenna element 10
Are accommodated in the case 15. Coaxial cable 16
Inner conductor 16a penetrates the dielectric substrate 11 and is connected to the antenna patch 12 on the surface thereof.

The antenna element 10 is arranged on the printed board 17. A circuit such as a preamplifier is arranged on the back side of the printed board 17. FIG. 7 is a diagram showing a circuit of the preamplifier. In this figure, the antenna elements 10 fed from two feeding points 90 ° out of phase are connected to the antennas 10Q and 10I.
Two antennas are shown. The two antennas 10Q and 10I are connected to the connectors CN-1 and CN.
-2 to be connected to the hybrid circuit 20. This hybrid circuit 20 includes two antennas 10Q and 10I.
The power supply current is distributed by changing the phase by 90 °.

The hybrid circuit 20 includes an amplifier IC 21.
It is connected to the. The amplifier IC21 amplifies the received signal in the first stage. The amplifier IC 21 is connected to the amplifier IC 24 via the bandpass filter 23. This amplifier IC24 is a bandpass filter 2
3, the signal whose predetermined frequency is selected is amplified.

The output of the amplifier IC 24 is connected to the inner conductor 16a of the coaxial cable 16 via the capacitor C6. The outer conductor 16b of the coaxial cable 16
Is connected to the ground of the printed circuit board. Also,
The inner conductor 16a of the coaxial cable 16 is superposed with a direct current of about 5 V, and the length is 1 / the wavelength of the center frequency.
4, the DC is taken out through the relatively thin microstrip line 25 of about 100Ω and the amplifier ICs 21 and 24 are connected.
Is being supplied as a power source. The capacitors C1 to C
Reference numerals 5 and C7 are for noise removal.

With such a preamplifier, the current excited by circular polarization and flowing through the antenna patch 12 is amplified and transmitted to the coaxial cable 16. The printed circuit board 17 is made of a resin having a dielectric constant of about 10, and the wiring on the printed circuit board 17 is composed of a 50Ω microstrip line (denoted by MSL50).

FIG. 8 is an overall layout of the printed circuit board 17 on which the preamplifier is mounted. In this way, the connector CNOUT (for signal output) is provided at one end (upper left) for connection with the vehicle body side, and the power supply line goes around the lower side,
The signal processing line goes around the right side to reach the central part.
The signal input terminals CN1 and CNQ connected to the hybrid circuit 20 are arranged directly below the feeding points fp1 and fp2. This allows connection with the antenna patch 12 with a relatively short pin.

Further, it is preferable that the amplifier ICs 21 and 24 are composed of bare chips and are connected to the microstrip line by wire bonding. FIG. 9 shows an amplifier I
The situation of wire bonding of C21 and C24 is shown. In the figure, the thick lines with a mark at both ends indicate wire bonding. As a result, the circuit can be downsized as a whole and sufficient characteristics can be obtained.

By combining such a preamplifier with the above-mentioned antenna element, the GPS antenna assembly 7 can be made compact and stable, and can be incorporated into the door mirror cover 1.

According to such a GPS antenna, the GP
The radio wave from the S satellite is received by the antenna patch 12, and this is transmitted via the preamplifier and the coaxial cable 16 to the GP.
Supplied to the S receiver. The GPS antenna assembly 7 is arranged on the back of the mirror 6. Therefore, the reflection from the building or the road surface is reflected by the antenna patch 1.
2 is unlikely to be received and can prevent false detections,
Positioning accuracy can be improved. Further, an electric mirror actuator is arranged outside the GPS antenna assembly 7. Therefore, the radio wave is also blocked by this, and erroneous detection due to the reflected wave can be prevented.

Further, since the antenna element is arranged on the substrate 17 of the preamplifier and is housed in the case, it is only necessary to connect the antenna element to the GPS receiver with a coaxial cable. That is, the antenna is adjusted so that it can perform a predetermined function at the time of manufacture. Therefore, at the time of installation, fine adjustment is not required for the antenna element, and the assembling work becomes very simple.

Here, this antenna element is a GP
Although it is used only for receiving S, the same configuration can be used for receiving other radio waves such as traffic information or a road beacon for collecting tolls on toll roads.

Further, by incorporating the present antenna in the two door mirrors, diversity reception can be easily achieved.

Since both the TV antenna and the GPS antenna are built in the door mirror, there is no problem in appearance.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a first embodiment.

FIG. 2 is a diagram showing a cross-sectional configuration of a second embodiment.

FIG. 3 is a diagram showing a front configuration in which the mirror of the embodiment is removed.

FIG. 4 is a diagram showing a configuration of an antenna element of the same embodiment.

FIG. 5 is a diagram showing an axial ratio characteristic of the configuration of the embodiment.

FIG. 6 is a diagram showing a configuration of a GPS antenna assembly of the same embodiment.

FIG. 7 is a circuit diagram showing a configuration of a preamplifier of the same embodiment.

FIG. 8 is a diagram showing an arrangement of briamplifiers according to the same embodiment.

FIG. 9 is a view showing a form of wire bonding of the bare chip of the same embodiment.

[Explanation of symbols]

1 door mirror cover, 2 TV antenna element, 3 coaxial cable, 4 first antenna element,
5 2nd antenna element, 6 mirror, 7 GPS antenna assembly, 8 mirror electric actuator.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Reference number in the agency FI Technical display location H01Q 23/00 H01Q 23/00

Claims (3)

[Claims] 1. A device in which an antenna element is installed in a door mirror case of a vehicle, wherein the antenna element includes a strip-shaped first antenna element and a linear second antenna element serially coupled to the first antenna element. An antenna device for a vehicle, comprising: a band surface of the first antenna element fixed to an inner surface of a door mirror case, and the second antenna element arranged on a vehicle mounting side in the door mirror case. 2. An apparatus in which an antenna element is installed in a door mirror case of a vehicle, wherein the antenna element is a GPS antenna, and the GPS antenna is arranged rearward of a mirror surface so as to face upward. . 3. The device according to claim 2, further comprising an electrically conductive actuator for changing an angle of the mirror surface, wherein the GPS antenna is on a vehicle front side of the mirror surface and in a vehicle width direction of the electrically conductive actuator. An antenna device for a vehicle, which is arranged inside or above the vehicle.