JP2000077923A - Automotive antenna - Google Patents

Abstract

(57) [Problem] To store a GPS antenna unit and a telephone antenna unit in a small antenna case. SOLUTION: GP formed on an oval metal base 3
The GPS antenna unit 4 is stored in the S antenna storage unit 3b. The telephone antenna section 5 is composed of a linear element section and a circular crown provided at the tip of the element section and bent downward to form an umbrella. Since the crown is bent downward, the capacitance generated between the crown and the metal base 3 acting as a ground plane increases, and the diameter of the crown can be reduced.
Thereby, the shape of the telephone antenna unit 5 can be reduced, and the telephone antenna unit 5 can be housed in the antenna case including the cover 2 and the metal base 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-vehicle antenna capable of transmitting / receiving or receiving signals in an in-vehicle telephone band and a GPS band.

[0002]

2. Description of the Related Art There are various types of antennas mounted on a vehicle body. However, if the antenna is mounted on the roof located at the highest position in the vehicle body, the receiving sensitivity can be increased. Preferred by Recently, GPS (Gl
Car navigation systems and in-vehicle telephones using the obal positioning system are becoming widespread, and it has been demanded that a GPS antenna used in the car navigation system and a telephone antenna used in the in-vehicle telephone be installed on the vehicle body. I have. In addition, separately installing a plurality of types of antennas on a vehicle body has problems in design and also complicates maintenance and mounting work. Therefore, a single antenna case has a vehicle-phone antenna unit and a GPS antenna unit. There is a demand for an in-vehicle antenna provided with.

[0003]

FIG. 14 shows an example of the configuration of this type of vehicle-mounted antenna. The vehicle-mounted antenna 100 shown in FIG. 14 includes a GPS antenna 104 for receiving a GPS signal and a telephone antenna 105 used for a vehicle-mounted telephone. These two types of antennas are mounted on an antenna case including a conductive metal base 103 and a synthetic resin cover 102 fitted to the metal base 103. Note that the telephone antenna 105 is a rod-shaped antenna, and is screwed to a mounting portion of the cover 102. The telephone antenna 105 is electrically connected to a circuit board 106 on which a matching circuit is incorporated.
Further, the GPS antenna 104 is housed in a housing formed on the metal base 103.

However, the above-described vehicle-mounted antenna 1
In the case of 00, since the rod-shaped telephone antenna 105 is provided upright from the cover 102, the overall height is increased. For this reason, when it attaches to a vehicle, a design problem arises and a handling problem arises. In addition, the protruding telephone antenna 105 may be broken or bent by an obstacle. By the way, the vehicle-mounted antenna 100 shown in FIG.
In order to reduce the size of the telephone antenna, the rod-shaped telephone antenna 105 may be reduced in size. As a method for reducing the size of the telephone antenna 105, a method using the helical antenna 110 shown in FIG.

However, in the helical antenna 110, if the antenna height H2 is suppressed, the antenna impedance becomes low, and it is difficult to match the antenna with the feed line. Therefore, the antenna height H2 cannot be reduced so much. Actually, assuming that the wavelength of the target frequency is λ, the antenna height H2 needs to be about 3λ / 16 to λ / 4, and it is not possible to reduce the size much. Further, even when the antenna height H2 of the helical antenna 110 is set to exceed 3λ / 16, the VSWR (voltage standing wave ratio) characteristic becomes a characteristic shown as “conventional” in FIG. 12, and the operable frequency range F1 is narrow. This is a band and is not suitable as a telephone antenna requiring a wide band. Furthermore,
Assuming that the antenna height H2 is 3λ / 16 or less, its VSW
The R characteristic is a characteristic shown as “conventional” in FIG. That is, the VSWR becomes 3 or more, and the antenna gain is greatly reduced.

As one method of reducing the size of the telephone antenna 105, a method of using the crown antenna 120 shown in FIGS. 16A and 16B as the telephone antenna 105 can be considered. The top crown antenna 120 includes an element portion 120b that stands upright on the substrate 120c, and a disk-shaped top crown portion 120a provided at the tip of the element portion 120b. By providing the top crown portion 120a at the tip of the element portion 120b, the top crown antenna 120a is provided.
Can be kept low. further,
The antenna impedance is not reduced, and matching can be easily achieved. However, if the antenna height H3 is reduced until the crown antenna 120 can be accommodated in the cover 102, the diameter D5 of the crown portion 120a increases, so that a large internal volume of the antenna case is required. 100 cannot be reduced in size.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a miniaturized in-vehicle antenna capable of housing a GPS antenna and a telephone antenna in a small antenna case.

[0008]

In order to achieve the above object, the present invention provides a vehicle-mounted antenna comprising a telephone antenna capable of receiving a radio telephone band, the telephone antenna being fixed, The telephone antenna unit, the circuit board and the GPS antenna unit include a circuit board provided with at least matching means, a GPS antenna unit, a conductive base, and a cover fitted to the base. The telephone antenna unit includes an antenna case housed therein, and the telephone antenna unit includes an element unit and a top cap provided at a tip of the element unit and bent downward.

Further, in the above-mentioned vehicle-mounted antenna, the top crown portion may be inclined downward to form an umbrella shape, or the top crown portion may be bent at least one step so as to be substantially orthogonal to the top crown portion. The crown portion may have a skeleton configuration including only a skeleton. Further, a matching stub having one end connected to a predetermined position of the element portion and the other end connected to the ground may be provided, or a shortening coil may be inserted into the element portion.

According to the present invention, since the GPS antenna unit and the telephone antenna unit are housed in the antenna case, a vehicle-mounted antenna having no protruding element can be provided. An in-vehicle antenna that is not broken or bent can be provided. Further, since the top crown of the telephone antenna is bent downward, the distance between the top crown and the ground plane is reduced, and the capacity of the top crown and the ground plane is increased. As a result, the diameter of the crown can be reduced, so that the antenna height can be reduced and a small telephone antenna can be provided. Thus, the in-vehicle antenna of the present invention
Since the telephone antenna unit can be housed in a small antenna case, and the entire vehicle-mounted antenna can be reduced in size, design problems are minimized even when the antenna is mounted on a vehicle body.

[0011]

1 (a), 1 (b) and 3 show the construction of an embodiment of a vehicle-mounted antenna according to the present invention. However, FIG. 1A is a top view of the in-vehicle antenna, and FIG.
FIG. 2 is a plan view, FIG. 2 is a cutaway plan view, and FIG. 3 is a perspective view with a cover removed. As shown in FIG. 1, an in-vehicle antenna 1 of the present invention includes an antenna case including an elliptical conductive metal base 3 and a synthetic resin cover 2 fitted to the metal base 3. ing. As shown in FIG. 2, a flexible pad 8 is arranged on the lower surface of the metal base 3 and attached to the vehicle body. It does not have any elements such as elements protruding from the antenna case. Further, on the back side of the metal base 3, a fixing screw portion 3a that fits into a mounting hole formed in the vehicle body and is screwed with a fixing screw to fix the vehicle-mounted antenna 1 to the vehicle body is formed to protrude. ing. The fixing screw portion 3a is provided with a through hole having a slit formed along the axis, and the GPS cable 10 and the telephone cable 11 are introduced into the antenna case from the outside using the through hole. Have been.

A connector 10a connected to GPS equipment is provided at the tip of the GPS cable 10, and a connector 11a connected to the vehicle telephone is provided at the tip of the telephone cable 11. As shown in FIG. 2 in which the metal base 3 and the cover 2 are cut away,
A GPS antenna unit 4 for receiving a GPS signal and a telephone antenna unit 5 for a vehicle-mounted telephone are housed. This GPS
The antenna unit 4 is housed in a GPS antenna housing 3b formed on the metal base 3. The telephone antenna unit 5 is electrically connected to a circuit board 6 in which the matching circuit shown in FIGS. 2 and 3 is incorporated, and is mechanically fixed. Then, the circuit board 6 is fixed to the metal base 3. The GPS cable 10 introduced into the antenna case is connected to the GPS antenna unit 4, and the telephone cable 11 is connected to the circuit board 6.

The GPS antenna housing 3b has a rectangular frame capable of housing the GPS antenna 4 formed on four sides, and a wave spring 4a having a waveform is provided in the GPS antenna housing 3b. The GPS antenna unit 4 is housed through. Although not shown, when the cover 2 is fitted to the metal base 3, the GPS antenna unit 4 is pressed by the pressing protrusion formed inside the cover 2 and held in the GPS antenna storage unit 3 b. You. In addition, the telephone cable 11 and the GPS cable 10
As shown in FIG. 2, when the fixing screw portion 3a is drawn out of the through hole of the fixing screw portion 3a, the fixing screw portion 3a can be laterally pulled out of a slit formed along the axis of the fixing screw portion 3a. It can also be pulled out vertically as shown by the dashed line. Thereby, the telephone cable 11 and the GPS cable 10 can be pulled out according to the structure of the vehicle body to which the vehicle-mounted antenna 1 is mounted.

The telephone antenna unit 5 comprises an umbrella-shaped top cap 5a and a linear element 5b which are bent downward, for example, as shown in the figure. A matching stub 5e is provided so as to connect between them. The matching stub 5e is for matching the telephone antenna section 5 and the telephone cable 11, and the top cap 5a is accommodated in a hemispherically bulged portion of the cover 2. Further, as shown in FIG. 2, a T-shaped pin 6a is provided so as to be inserted from the back surface of the circuit board 6 and protrude from the front surface, and a T-shaped pin 6a formed by projecting an element portion 5b formed of a metal pipe. The element portion 5b is formed by being inserted. Further, the tip of the element portion 5b is inserted into a through hole provided substantially at the center of the umbrella-shaped top crown portion 5a, and is fixed by soldering or the like.

The telephone antenna section 5 can have various configurations. The configuration shown in FIGS. 2 and 3 is an example, and FIGS. 4 to 11 show other configuration examples. FIG. 4 shows a first configuration example of the telephone antenna unit 5. FIG. 4A is a top view of the telephone antenna unit 5, and FIG. As shown in these figures, the telephone antenna section 5 of the first configuration example has a linear element section 5b and a circular top provided at the tip of the element section 5b and bent downward to form an umbrella. And a crown 5a. Further, a flange-shaped crown mounting portion 5c is formed at the tip of the element portion 5b, and the crown mounting portion 5c is formed on the crown mounting portion 5c.
Are fixed by soldering or the like. Further, a flange-shaped mounting portion 5d is formed at the lower end of the element portion 5b,
The mounting portion 5d is fixed to a pattern formed on the circuit board 6 by soldering. At this time, the element portion 5b is connected to a matching circuit provided on the circuit board 6. When the circuit board 6 is mounted on the metal base 3, the ground pattern of the circuit board 6 is electrically connected to the metal base 3, and the metal base 3 is connected to the telephone antenna 5.
To act as a ground plane.

Since the top crown 5a of the telephone antenna unit 5 is bent downward so as to form an umbrella, the capacity formed between the metal base 3 serving as a ground plane and the top crown 5a is large. Thus, the diameter D2 of the top crown 5a can be reduced. For example, this telephone antenna unit 5
Is a digital cellular system, GSM (Gl
obal System for Mobile communications), the diameter D2 of the crown 5a is about 30 mm.
And the antenna height H1 is about 25.8 mm. This value is larger than that of the conventional crown antenna 120 shown in FIG. 16 which is applied to the GSM system with the same antenna height, and the diameter D5 of the crown crown 120a is required to be 40 mm. Can be reduced by 30% or more. The uplink frequency of the GSM system is 890-915M
Hz and the downstream frequency is 935 to 960 MHz.

Next, FIG. 5 shows a second configuration example of the telephone antenna unit 5. FIG. 5 (a) is a top view of the telephone antenna unit 5, and FIG. Indicated by. As shown in these figures, the telephone antenna section 5 of the second configuration example has a linear element section 5b and this element section 5b.
And a circular top crown 5a provided at the tip of the head. The top crown 5a is bent downward at a substantially right angle at its tip so that its cross section becomes L-shaped. A flange-shaped top cap mounting portion 5c is provided at the tip of the element portion 5b.
Is formed, and the top crown portion 5a is fixed to the top crown mounting portion 5c by soldering or the like. At the lower end of the element portion 5b, a flange-shaped mounting portion 5d is formed, and the mounting portion 5d is fixed to a pattern formed on the circuit board 6 by soldering. At this time, the element section 5b is connected to a matching circuit provided on the circuit board 6. When the circuit board 6 is attached to the metal base 3,
The ground pattern of the circuit board 6 is electrically connected to the metal base 3, and the metal base 3 functions as a ground plane of the telephone antenna unit 5.

Since the top crown 5a of the telephone antenna unit 5 is bent downward at a substantially right angle, the capacity formed between the metal base 3 serving as a ground plane and the top crown 5a increases. The diameter D3 of the crown 5a can be reduced. For example, this telephone antenna unit 5
When applied to an M-type antenna, the diameter D3 of the crown 5a
Is about 30 mm, and the antenna height is about 25.8 mm. Therefore, the size of the diameter can be reduced by 30% or more compared to the conventional crown antenna 120.

Next, FIG. 6 shows a third configuration example in which the second configuration example of the telephone antenna unit 5 is improved. FIG. 6 (a) is a top view of the telephone antenna unit 5, and FIG. ) Shows the plan view in a half section. As shown in these figures, the telephone antenna section 5 of the third configuration example is a linear element section 5b.
And a circular crown 5a provided at the tip of the element 5b. The top crown 5a is bent substantially perpendicularly over two steps downward so that the cross section of the top is U-shaped. A flange-shaped top cap mounting portion 5c is formed at the tip of the element portion 5b.
The top crown portion 5a is fixed to the top crown mounting portion 5c by soldering or the like. At the lower end of the element portion 5b, a flange-shaped mounting portion 5d is formed, and the mounting portion 5d is fixed to a pattern formed on the circuit board 6 by soldering. At this time, the element section 5b is connected to a matching circuit provided on the circuit board 6. When the circuit board 6 is mounted on the metal base 3, the ground pattern of the circuit board 6 is electrically connected to the metal base 3, and the metal base 3 functions as a ground plane of the telephone antenna unit 5. Become.

The top crown 5a of the telephone antenna unit 5 is bent downward at substantially right angles in two steps, so that the metal base 3 serving as a ground plane and the top crown 5a are formed.
And the capacitance formed between them becomes large, and the diameter D4 of the top crown 5a can be made smaller. For example, when the telephone antenna unit 5 is applied to a GSM type antenna, the diameter D4 of the crown 5a is about 25 mm, and the antenna height is about 25.8 mm. Therefore, the size of the diameter can be reduced by about 17% compared with the telephone antenna section 5 of the second configuration example.

Next, FIG. 7 shows a fourth configuration example of the telephone antenna unit 5. FIG. 7A is a top view of the telephone antenna unit 5, and FIG. Indicated by. As shown in these figures, in the telephone antenna section 5 of the fourth configuration example, a matching stub 5e is provided on the linear element section 5b to facilitate matching. This matching stub 5e
Is connected to a predetermined position of the element portion 5b, and the other end is connected to a ground pattern formed on the circuit board 6. In FIG. 7, the top crown 5a is bent downward so as to form an umbrella, but the top crown 5a is bent downward at a substantially right angle (see FIG. 5). Alternatively, the shape may be such that the tip is bent substantially perpendicularly over two steps downward (see FIG. 6).

Next, FIG. 8 shows a fifth configuration example of the telephone antenna unit 5. FIG. 8A is a top view of the telephone antenna unit 5, and FIG. Indicated by. As shown in these figures, in the telephone antenna section 5 of the fifth configuration example, the shortening coil 5f is inserted into the linear element section 5b so that the length of the element section 5b can be further reduced. Further, a matching stub 5e is provided on the element portion 5b.
Are provided so that the alignment can be easily achieved even when the shortening coil 5f is inserted. One end of the matching stub 5e is connected to a predetermined position of the element portion 5b, and the other end is connected to an earth pattern formed on the circuit board 6. In FIG. 8, the top crown 5a is bent downward so as to have an umbrella shape, but the top crown 5a is bent downward at a substantially right angle (see FIG. 5). And
It may have a shape (see FIG. 6) in which the front end is bent substantially perpendicularly over two steps downward.

Next, FIG. 9 shows a sixth example of the configuration of the telephone antenna unit 5. FIG. 9A is a top view of the telephone antenna unit 5, and FIG. Indicated by. As shown in these figures, in the telephone antenna section 5 of the sixth configuration example, the top cap section 5a has a skeleton configuration of only its skeleton. Even if the crown 5a has the skeleton configuration, the capacitance generated between the crown 5a and the ground plane does not decrease, and the diameter of the crown 5a can be made smaller than before. In FIG. 9, the crown 5a is bent downward so as to have an umbrella shape.
The shape of “a” is a shape in which the tip is bent downward at a substantially right angle (see FIG. 5), or a shape in which the tip is bent downward substantially in two steps (see FIG. 6), and the top crown 5a is a skeleton. It may be configured.

Next, FIG. 10 shows a seventh example of the telephone antenna unit 5.
10A shows a top view of the telephone antenna unit 5 and FIG. 10B shows a plan view of the antenna unit 5 in a half section. As shown in these figures, in the telephone antenna section 5 of the seventh configuration example, the space between the top crown section 5a and the circuit board 6 is filled with a dielectric 7. Thereby, the capacitance generated between the top crown 5a and the ground plane increases according to the relative dielectric constant of the dielectric 7, so that the diameter of the top crown 5a can be further reduced. In FIG. 10, the top crown 5a is bent downward so as to have an umbrella shape. However, the top crown 5a is shaped such that the tip is bent downward at a substantially right angle (see FIG. 5). Alternatively, the space between the top crown 5a and the ground plane may be filled with the dielectric 7 in a shape in which the tip is bent substantially perpendicularly over two steps downward (see FIG. 6). In addition, the top cap 5a may be formed by depositing a conductive thin film on the dielectric 7 or attaching a thin metal plate.

Next, FIG.
FIG. 11A shows a top view of the telephone antenna unit 5 and FIG. 11B shows a plan view of the antenna unit 5 in a half section. As shown in these figures, in the telephone antenna section 5 of the eighth configuration example, the inside of the dielectric 7 filled between the top crown section 5a and the circuit board 6 is made hollow. Even in this case, since the capacitance generated between the top crown 5a and the ground plane increases in accordance with the relative dielectric constant of the dielectric 7, the top crown 5
It becomes possible to make the diameter of a smaller. In FIG. 10, the top crown 5a is bent downward so as to have an umbrella shape. However, the top crown 5a is shaped such that the tip is bent downward at a substantially right angle (see FIG. 5). Alternatively, the space between the top crown 5a and the ground plane may be filled with the dielectric 7 in a shape in which the tip is bent substantially perpendicularly over two steps downward (see FIG. 6). In addition, the top cap 5a may be formed by depositing a conductive thin film on the dielectric 7 or attaching a thin metal plate.

The electrical characteristics of the telephone antenna section 5 in the first to eighth configuration examples thus configured are substantially the same. For example, FIG. 12 and FIG. 13 show the VSWR frequency characteristics of the telephone antenna unit 5 of the fourth configuration example shown in FIG. FIG. 12 shows that the antenna height is 3λ / 16.
(Λ: wavelength of the target frequency) is a VSWR characteristic when it exceeds the frequency band F2 in which operation is possible as shown in FIG. 12 as “the present invention”. Understand. FIG. 13 shows the VSWR characteristics when the antenna height is within 3λ / 16. As shown in FIG.
It can be seen that the frequency range below 2.0 is wide and the band is suitable as a telephone antenna.

[0027]

Since the present invention is constructed as described above, the GPS antenna unit and the telephone antenna unit are housed in the antenna case, so that a vehicle-mounted antenna having no protruding element portion can be obtained. In addition, the vehicle-mounted antenna can be prevented from being broken or bent by an obstacle. Further, since the top crown of the telephone antenna is bent downward, the distance between the top crown and the ground is reduced, and the capacity of the top crown and the ground is increased. As a result, the diameter of the crown can be reduced, so that the antenna height is low and a small telephone antenna can be obtained. in this way,
The in-vehicle antenna of the present invention can accommodate the telephone antenna section in a small antenna case, and can reduce the size of the in-vehicle antenna as a whole. It will not occur as much as possible.

[Brief description of the drawings]

FIG. 1 is a top view and a plan view showing a configuration of an embodiment of a vehicle-mounted antenna according to the present invention.

FIG. 2 is a cutaway plan view showing a configuration of an on-vehicle antenna according to an embodiment of the present invention.

FIG. 3 is a perspective view showing a configuration of an on-vehicle antenna according to an embodiment of the present invention with a cover removed.

FIG. 4 is a diagram showing a first configuration example of a telephone antenna unit in the vehicle-mounted antenna according to the embodiment of the present invention.

FIG. 5 is a diagram showing a second configuration example of the telephone antenna unit in the vehicle-mounted antenna according to the embodiment of the present invention.

FIG. 6 is a diagram showing a third configuration example of the telephone antenna unit in the vehicle-mounted antenna according to the embodiment of the present invention.

FIG. 7 is a diagram illustrating a fourth configuration example of the telephone antenna unit in the vehicle-mounted antenna according to the embodiment of the present invention.

FIG. 8 is a diagram showing a fifth configuration example of the telephone antenna unit in the vehicle-mounted antenna according to the embodiment of the present invention.

FIG. 9 is a diagram showing a sixth configuration example of the telephone antenna unit in the vehicle-mounted antenna according to the embodiment of the present invention.

FIG. 10 is a diagram illustrating a seventh configuration example of the telephone antenna unit in the vehicle-mounted antenna according to the embodiment of the present invention.

FIG. 11 is a diagram showing an eighth configuration example of the telephone antenna unit in the vehicle-mounted antenna according to the embodiment of the present invention.

FIG. 12 is a diagram showing VSWR characteristics of a telephone antenna unit in a vehicle-mounted antenna according to an embodiment of the present invention in comparison with a conventional antenna.

FIG. 13 is a diagram showing VSWR characteristics of a telephone antenna unit in a vehicle-mounted antenna according to an embodiment of the present invention in comparison with a conventional antenna.

FIG. 14 is a cross-sectional view illustrating a configuration of a conventional vehicle-mounted antenna.

FIG. 15 is a diagram showing a configuration of a helical antenna used as a telephone antenna unit in a conventional vehicle-mounted antenna.

FIG. 16 is a diagram showing a configuration of a top crown antenna used as a telephone antenna unit in a conventional vehicle-mounted antenna.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1,100 In-vehicle antenna 2,102 Cover 3,103 Metal base 3a Fixing screw part 3b Antenna storage part 4,104 GPS antenna part 4a Wave spring 5,105 Telephone antenna part 5a, 120a Top cap part 5b, 120b Element part 5c Top cap attachment part 5d Attachment part 5e Matching stub 5f Shortened coil 6, 106, 120c Circuit board 6a T-shaped pin 7 Dielectric 8 Pat 10 GPS cable 10a, 11a Connector 11 Telephone cable 110 Helical antenna 120 Top antenna

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01Q 23/00 H01Q 23/00 F term (Reference) 5J021 AA02 AA06 AA13 AB02 AB06 CA01 HA05 HA07 HA10 JA07 JA08 5J045 AB05 DA08 HA06 KA01 LA01 MA04 NA04 NA06 5J046 AA07 AA14 AB00 AB06 MA09 MA13 MA16 5J047 AA07 AA14 AB00 AB06 EB00

Claims (6)

[Claims] 1. A telephone antenna unit capable of receiving a telephone band, a circuit board to which the telephone antenna unit is fixed and at least matching means is provided, a GPS antenna unit, and a conductive base And a cover fitted to the base, comprising: the circuit board to which the telephone antenna unit is fixed; and an antenna case in which the GPS antenna unit is housed. An on-vehicle antenna, comprising: a linear element portion; and a top crown portion provided at a tip of the element portion and bent downward. 2. The on-vehicle antenna according to claim 1, wherein the crown is inclined downward to form an umbrella. 3. The apparatus according to claim 1, wherein the tip of the crown is substantially orthogonal.
2. The in-vehicle antenna according to claim 1, wherein the antenna is bent at least one step. 4. The in-vehicle antenna according to claim 1, wherein a matching stub having one end connected to a predetermined position of the element portion and the other end connected to ground is provided. 5. The on-vehicle antenna according to claim 1, wherein a shortening coil is inserted into the element portion. 6. The on-vehicle antenna according to claim 1, wherein the top cap portion has a skeleton configuration including only a skeleton.