JPH09181525A - On-vehicle antenna system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to arrange a compact integrated body consisting of plural antennas having different object frequency bands in a vehicle by mutually connecting the lower parts of a T-shaped antenna and a reverse L-shaped antenna and forming an integrated body. SOLUTION: Two pairs of antenna elements 11, 12 are formed based upon a diversity system. The element 11 consists of a metallic plate integrally formed by mutually connecting the lower parts of an reverted L-shaped antennas 11b, 11b through a T-shaped antenna 11a. The element 12 consists of a metallic plate integrally formed by mutually connecting the lower parts of a T-shaped antenna 12a and a reverse L-shaped antenna 12b. These elements 11, 12 are erected on a rectangular ground plate in parallel along its longitudinal direction. The ground plate 13 is constituted of forming a copper foil layer on the erected parts of the elements 11, 12 and two antenna connection terminals 15, 16 are formed through a wiring pattern 14 directly led out from the lower part of the element 11 is formed on the surface of the copper foil layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle-mounted antenna device for transmitting and receiving radio waves in a plurality of frequency bands used in, for example, mobile phones and GPS navigation devices.

[0002]

2. Description of the Related Art Recently, mobile phones for automobiles have become widespread,
While the frequency band used is expanded to the 1.5 GHz band as well as the 800 MHz band, the GPS (Global)
Positioning System) navigation devices that use radio waves coming from satellites have also become widespread, and VICS that uses radio wave beacons in the near future.
(Vehicle Information & Co
As communication media used in automobiles increases, the number of antennas that must be installed in automobiles and that correspond to each frequency band used will also increase. It is in.

[0003]

When a large number of antennas must be mounted on one vehicle as described above,
Not only does this impair the appearance, but it also causes problems such as damage and theft, and wiring problems such as having to pull in multiple wires from outside the vehicle to the inside of the vehicle.

The present invention has been made in view of the above situation, and an object thereof is to make a plurality of antenna elements having different target frequency bands into one and to install it in a vehicle in a small size. Is to provide an in-vehicle antenna device.

[0005]

According to the first aspect of the present invention,
A T-shaped antenna and at least one inverted L-shaped antenna having a target frequency band higher than that of the T-shaped antenna are integrally formed by connecting their lower parts to each other, and the antenna element is erected, and at least the antenna element is erected. It is characterized by comprising a ground plane for feeding power to the antenna element from a gap portion of a metal foil formed on one surface.

With such a structure, a plurality of antennas having different target frequency bands can be integrated into a small size as a set of antennas, and can be sufficiently installed in a vehicle.

According to a second aspect of the present invention, there is provided a diversity system comprising a T-shaped antenna and at least one inverted L-shaped antenna having a target frequency band higher than that of the T-shaped antenna, the lower part of which is integrally connected to form a metal flat plate. 2 or more sets of antenna elements and these antenna elements are erected,
A ground plane that feeds each antenna element through a gap portion of a metal foil formed on at least one surface and one of the corresponding T-shaped antenna or inverted L-shaped antenna of the two or more sets of antenna elements are used for the first mobile communication. This reception signal of the second mobile communication is dedicated to reception or transmission, and the other is used for both transmission and reception, the first mobile communication and the reception of the second mobile communication close to the target frequency band. And a filter circuit for extracting the frequency band component of.

With such a structure, it is possible to support a diversity system and to integrate a plurality of antennas having different target frequency bands into a small unit as a set of antennas, which can be sufficiently installed in a vehicle. In addition, especially for two antennas close to each other in the target frequency band, one antenna is shared, and the number of antennas forming one set of antenna elements is reduced,
Further, it can contribute to miniaturization.

The invention according to claim 3 is the invention according to claim 1 or 2, further comprising a matching circuit for performing impedance matching between the T-shaped antenna of the antenna element and at least one inverted L-shaped antenna. It is characterized by

With such a structure, in addition to the operation of the invention described in claim 1 or 2, by matching between a plurality of antennas forming one set of antenna elements, transmission / reception characteristics of each antenna can be obtained. Can be improved.

According to a fourth aspect of the present invention, in the second aspect of the present invention, the T-shaped antenna of the antenna element is used to move the mobile phone in the 800 MHz band, and the first inverted L-shaped antenna is used to move the mobile phone in the 1.5 GHz band. Body phone and 1.575 GHz
A band GPS signal is targeted, and the filter circuit extracts the GPS signal from the reception signal of the first inverted L-shaped antenna.

With such a structure, in addition to the operation of the invention described in claim 2, it is possible to deal with both the 800 MHz band and the 1.5 GHz band which are set in the mobile phone for automobiles. In addition, the mobile phone for automobiles in the 1.5 GHz band and the antenna for receiving GPS signals in the 1.575 GHz band used in navigation devices and the like in which the target frequency band is close to each other can be shared.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing the basic external configuration, and 11 and 12 are two sets of antenna elements provided based on the diversity method.

The antenna element 11 is centered on a T-shaped antenna 11a intended for a mobile telephone for automobiles in the 800 MHz band, and the T-shaped antenna 11a is sandwiched between the antenna element 11 and a mobile telephone for automobiles in the 1.5 GHz band and 1.575G.
Inverted L-shaped antenna 11 for Hz GPS signal 11
b and VI using a radio beacon in the 2.499 GHz band
The inverted L-shaped antenna 11c intended for CS is composed of a metal flat plate integrally formed by connecting the lower part thereof. For example, a copper plate, a tin plate, a brass plate or the like is pressed, and then the inverted L-shaped antenna 11b is formed. And inverted L-shaped antenna 1
As shown in the figure, 1c and 1c are formed by bending the lower part of the leg into a crank shape so that their directions are different from each other.

The antenna element 12 has almost the same structure as that of the antenna element 11 except that there is no portion corresponding to the inverted L-shaped antenna 11c for VICS. The target T-shaped antenna 12a and the inverted L-shaped antenna 12b targeted for a 1.5 GHz band mobile telephone for automobiles are made of a metal flat plate integrally formed by connecting the lower portions thereof.

The antenna elements 11 and 12 are both erected in parallel on the rectangular base plate 13 along the longitudinal direction.
The ground plate 13 will be described in detail later, but for example, the antenna elements 11 and 12 on the almost entire back surface and the front surface of the epoxy glass substrate.
A copper foil layer is formed on an upright portion, and two antenna connection terminals 15 and 16 are formed on the surface of the copper foil layer via a wiring pattern 14 directly derived from a lower portion of the antenna element 11.
Further, a GPS signal selection circuit 17, which will be described later, is surface-mounted so as to be derived from the wiring pattern 14, and
A wiring pattern 18 and an antenna connection terminal 19 are further formed via the GPS signal selection circuit 17.

The wiring pattern 14 is the antenna element 1
1 always operates as an antenna of three frequency bands, so that the transmission and reception characteristics of each do not deteriorate.
The impedance matching circuit 20 is configured.

Further, an antenna connection terminal 22 is formed on the surface of the base plate 13 via a wiring pattern 21 directly led out from the lower portion of the antenna element 12. In the diversity system configuration as described above, one antenna element 12
Is fixedly used for receiving only, and is a mobile body for an automobile of 800 MHz band by T-shaped antenna 12a or 1.5 GHz band by inverted L-shaped antenna 12b (these cannot be used at the same time). The received signal of the telephone is taken out from the antenna connection terminal 19 via the wiring pattern 18.

Further, the other antenna element 11 is used by switching between transmission and reception of an automobile mobile telephone of 800 MHz band by the T-shaped antenna 11a or 1.5 GHz band by the inverted L-shaped antenna 12b. The inverted L-shaped antenna 12b extracts a reception signal of a GPS signal in the 1.575 GHz band, and the inverted L-shaped antenna 11c extracts a reception signal of a VICS radio wave beacon of 2.499 GHz.

Next, a detailed structure of the antenna elements 11 and 12 will be described. 2A and 2B show the antenna element 1.
1 is a front view and FIG. 2 (b) is a right side view. As described above, the antenna element 11 has the inverted L-shaped antenna 11b and the inverted L-shaped antenna 11c whose lower portions are coupled to each other around the T-shaped antenna 11a. It is composed of a metal flat plate integrally formed, and as shown in FIG. 2A, a T-shaped antenna 11a.
A slight slit is formed between the legs of the antenna and the tops and legs of the inverted L-shaped antennas 11b and 11c.
The L-shaped antenna 11b and the inverted L-shaped antenna 11c are shown in FIG.
As shown in (b), the lower portions of the legs are bent and formed in a crank shape so that the directions are different from each other. Also,
At the lower end of the T-shaped antenna 11a, a protrusion 11d for inserting into the base plate 13 and standing upright is provided.

2A and 2B show the structure of the antenna element 11, the antenna element 1
2 has a configuration in which the inverted L-shaped antenna 11c of the antenna element 11 is omitted, and therefore the description of the configuration of the antenna element 12 is omitted.

However, in contrast to the above-described antenna elements 11 and 12, the base plate 13 which stands them is constructed as shown in FIG. FIG. 3A shows the wiring pattern 1 described above.
4, 18, 21 and antenna connection terminals 15, 16, 19,
22 shows a basic configuration on the front surface side of the main plate 13 excluding the GPS signal selecting circuit 17 and the GPS signal selecting circuit 17.
Ground areas 33 and 34 made of copper foil are formed around slits 31 and 32 formed for inserting the protrusions 11d (, 12d) at the lower end of the.

As shown in FIG. 3 (b), the bottom surface of the base plate 13 is spaced at regular intervals from the ground areas 35 and 36 made of copper foil centered on the slits 31 and 32, respectively.
For example, a gap having a width of 1 [mm] is provided and the copper foil layer 37 is formed on the entire other surface, and power is supplied to the antenna elements 11 and 12 from the gap.

The slits 31 and 32 have a width m and a plate thickness T of the protrusions 11d (, 12d) for inserting the protrusions 11d (, 12d) at the lower ends of the antenna elements 11, 12, respectively, for example, 0.1. The slits 31 and 32 are formed by fitting with a slight margin for each [mm], and soldering is performed with the protrusions 11d (, 12d) at the lower ends of the antenna elements 11 and 12 inserted into the slits 31 and 32. , Antenna elements 11 and 12 are erected on the ground plane 13,
12 and the ground areas 33 and 34 on the front surface of the main plate 13 and the ground areas 35 and 36 on the back surface thereof are electrically connected to each other.

FIG. 4 shows a circuit configuration centered on the GPS signal selection circuit 17 and the impedance matching circuit 20 and provided on the ground plane 13 and connected to the antenna element 11.

The GPS signal selecting circuit 17 is a narrow band GPS for extracting a GPS signal from the signals received by the inverted L-shaped antenna 11b of the antenna element 11 obtained via the wiring pattern 14 and the impedance matching circuit 20. Bandpass filter (BPF) 41 and this GPS BP
It is composed of a GPS preamplifier 42 that amplifies the GPS signal obtained in F41 to a certain level.

That is, as shown in FIG. 5, 1.5 GHz
To be precise, the mobile phone for automobiles in the band is 1.429 GHz.
To 1.453 GHz is the frequency band for transmission, 1.47 GHz
The frequency band for reception is 7 GHz to 1.501 GHz, whereas the frequency band of the GPS signal is 1.
Since it is 575 GHz, the GPS BPF 4 described above is used.
1 passes only this GPS signal component and is amplified by the GPS preamplifier 42. Therefore, the GPS signal amplified by the GPS preamplifier 42 is led to the GPS decoder (not shown) from the antenna connection terminal 19 via the wiring pattern 18.

Next, specific dimensions of each part including the antenna elements 11 and 12 will be illustrated. Here, as shown in FIG. 2, the plate thickness of each part of the antenna element 11 is T, the length of the top of the T-shaped antenna 11a is L1, the width of the top is W1, and the height from the surface of the main plate 13 to the center of the top is. Let H1 be the width of the same leg, and let M1 be the width of the top of the inverted L-shaped antenna 11b including L2 including the width of the slit to the leg of the T-shaped antenna 11a.
3 The height from the surface to the center of the same top is H2, the width of the same leg is M2, and the length of the top of the inverted L-shaped antenna 11c is L3 including the width of the slit to the T-shaped antenna 11a leg.
, The width of the top is W3, the height from the surface of the main plate 13 to the center of the top is H3, the width of the leg is M3, and the antenna element 11 formed at the lower end of the leg of the T-shaped antenna 11a is attached to the base plate 13. The width of the protrusion 11d for standing is set to m (m <m
M1) and the protrusion amount of the protrusion 11d is t.

The distance from the surface of the main plate 13 to the lower surface of the bent portion of the inverted L-shaped antenna 11b is h2, and the distance between the center positions of the plate surfaces of the T-shaped antenna 11a and the inverted L-shaped antenna 11b due to the bent portion. Is n2, the distance from the surface of the ground plane 13 to the lower surface of the bent portion of the inverted L-shaped antenna 11c is h3, and the T-shaped antenna 11a and the inverted L-shaped antenna 11 are formed by the bent portion.
The distance between the center positions of the plate surfaces of c is n3.

800M received by the T-shaped antenna 11a
The wavelength in the Hz band is λ 1, the wavelength in the 1.5 GHz band received by the inverted L-shaped antenna 11 b is λ 2, the inverted L-shaped antenna 11
If the wavelength of the 2.499 GHz band received at c is .lambda.3, the lengths L1 to L3 and the heights H1 to H3 are L1 = 0.22.lambda.1 H1 = 0.15.lambda.1 L2 = 0.1.lambda.2 H2 = 0.177.lambda.2 L3. = 0.1λ3 H3 = 0.18λ3, the resonance frequency of each antenna can be adjusted to the used frequency.

At this time, the widths W1 to W3 of the respective antennas are
In order to maximize the gain, W1 = 0.03λ1 W2 = 0.034λ2 W3 = 0.034λ3.

The widths M1 to M3 of the legs of each antenna
Can be set wide to widen the band,
Since the gain deteriorates, M1 = 0.034λ1 M2 = 0.024λ2 M3 = 0.024λ3 is obtained by selecting a value that satisfies the use band and maximizes the gain.

By setting the distances n2 and n3 large, the receiving band of the T-shaped antenna 11a can be improved.
On the contrary, if it is made small, impedance matching cannot be taken as a matter of course, so considering the range that does not impair the compactness of the entire antenna element, n2 = 0.015λ2, n3 =
It becomes 0.015λ3.

Further, the distances h2 and h3 are determined by the respective antennas 11
In order to achieve impedance matching for each of a to 11c, the depth of the slit formed so as to sandwich the leg portion of the T-shaped antenna 11a has an influence, so that the bent portion is formed at an optimum position. Then, h2 = 0.03λ2, h3 = 0.03λ3.

The plate thickness T is 0.8 [mm] and 0.5 [m]
m] did not show any change in the performance in the result of the experiment, therefore, it is sufficient to select a value that satisfies external environmental conditions such as vibration of the automobile and is further lightweight and low cost. .

The projection amount t of the projections 11d and 12d at the lower ends of the antenna elements 11 and 12 is a value obtained by subtracting 0.1 mm from the thickness of the base plate 13, and the projections 11d and 1d are
When 2d is inserted into the main plate 13, the lower end tip face thereof does not protrude from the rear face of the main plate 13.

As a material of the metal flat plates constituting the antenna elements 11 and 12, it has been confirmed by experiments that substantially the same performance can be obtained with any of copper plates, tin plates, brass plates, etc. as described above. It is only necessary to select a material that is lightweight and low cost.

Next, each dimension of the base plate 13 will be described.
Here, as shown in FIG. 3, the length of the long side of the main plate 13 is a,
The length of the short side is b, and the ground areas 33, 3 including the gap
The width along the direction of the slits 31, 32 of 4 is X, and the slits 31, 32 of the grounding regions 33, 34 including the same gap
Y along the direction orthogonal to the slits 31 and 32
Let D be the distance between the respective center positions and be e be the offset amount from the center position of the short side of the main plate 13 to the slits 31, 32.

The width X of the ground areas 33 and 34 including the gap is set to X = M1 + M2 + M3 + 6 [mm] in consideration of the above M1 to M3. The length Y of the ground areas 33 and 34 including the gap is Y = 0.06λ1.

The distance D between the center positions of the slits 31 and 32 is D = 0 because of the balance between the low correlation function of the antenna elements 11 and 12 and the compactness of the entire apparatus. .265λ1.

Further, the slit 3 is formed from the center of the short side of the main plate 13.
The offset amount e up to 1 and 32 is set to e = 0.03λ1 because it is easily affected by the glass when it is installed in the rear tray behind the rear seat as an on-vehicle antenna device.

When the above is summarized, the length a of the long side and the length b of the short side of the base plate 13 are a = 0.488λ1, b = 0 from the viewpoint of making the whole compact. The optimum value is .18λ1.

When the antenna device according to the embodiment of the present invention is constructed by using the respective dimensions as described above, 800
Gain of 2.15, which is substantially equivalent to that of a normal dipole antenna, for mobile phones for automobiles in the MHz band and the 1.5 GHz band
[DBI] can be obtained and can be sufficiently put to practical use.

Further, in place of the antenna elements 11 and 12 shown in FIGS. 1 and 2, the inverted L-shaped antennas 11b and 11c (12a and 12b) are respectively replaced by T as shown in FIG.
By using a left-right symmetric antenna with respect to the letter-shaped antenna 11a (12a), it is possible to improve the directivity and obtain an antenna device capable of transmitting and receiving radio waves from all directions on the moving body. .

In the above embodiment, the antenna device is used as an automobile mobile phone in the 800 MHz band and the 1.5 GHz band, the GPS signal in the 1.575 GHz band, and 2.49.
Although it has been described as being used for each transmission / reception of VICS by the 9 GHz radio beacon, the present invention is not limited thereto.

Further, in FIG. 1 and others, the structure in which the antenna elements 11 and 12 are erected on the main plate 13 is shown. However, when actually installed as a vehicle-mounted antenna, for example, in a rear tray in a car, these are mounted. It is also possible to attach a cover made of a dielectric material that does not greatly affect transmission and reception, such that it is integrally included. In addition, the present invention can be variously modified without departing from the scope of the invention and can be applied to transmission and reception of various signals in other frequency bands.

[0047]

As described above in detail, according to the present invention, it is possible to provide a small vehicle-mounted antenna device that can be installed in a vehicle by combining a plurality of antenna elements having different target frequency bands into one. it can.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a basic external configuration according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of an antenna element according to the same embodiment.

FIG. 3 is a diagram showing a basic configuration of a main plate according to the same embodiment.

FIG. 4 is a diagram mainly showing a circuit configuration of a GPS signal selection circuit according to the same embodiment;

FIG. 5 is a diagram for explaining the operation of the GPS signal selection circuit.

FIG. 6 is a diagram showing another configuration of the antenna element according to the same embodiment.

[Explanation of symbols]

 11, 12 ... Antenna element 11a, 12a ... T-shaped antenna 11a, 11b, 12b ... Inverted L-shaped antenna 11d ... Protrusion 13 ... Base plate 14, 18, 21 ... Wiring pattern 15, 16, 19, 22 ... Antenna connection terminal 16 ... Antenna connection terminal 17 ... GPS signal selection circuit 20 ... Impedance matching circuit 22 ... Antenna connection terminal 31, 32 ... Slits 33, 34, 35, 36 ... Ground area 41 ... GPS hand pass filter (BPF) 42 ... GPS preamplifier

Claims (4)

[Claims] 1. An antenna element comprising a T-shaped antenna and at least one inverted L-shaped antenna having a target frequency band higher than that of the T-shaped antenna, the lower part of which is integrally formed by integrally forming a metal flat plate, and the antenna element. An in-vehicle antenna device, comprising: a ground plate that is provided upright and feeds the antenna element through a gap portion of a metal foil formed on at least one surface. 2. Two or more antennas of the diversity type which are formed by a metal plate in which a T-shaped antenna and at least one inverted L-shaped antenna having a target frequency band higher than that of the T-shaped antenna are integrally formed by connecting their lower parts. Elements, a ground plane for arranging these antenna elements upright and feeding each of the antenna elements through a gap portion of a metal foil formed on at least one surface, and a T-shaped antenna or an inverted L-shaped antenna corresponding to the two or more antenna elements. One of them is dedicated to the reception or transmission of the first mobile communication, and the other is used for both transmission and reception and reception of the first mobile communication and the second mobile communication in the vicinity of the target frequency band. And a filter circuit for extracting the frequency band component of the received signal of the second mobile communication. 3. The vehicle-mounted antenna device according to claim 1, further comprising a matching circuit that performs impedance matching between the T-shaped antenna of the antenna element and at least one inverted L-shaped antenna. 4. The T-shaped antenna of the antenna element is 8
A mobile phone in the 00 MHz band is converted to a mobile phone in the 1.5 GHz band and a GPS (Global Positioning S) in the 1.575 GHz band by the first inverted L-shaped antenna.
3. The vehicle-mounted antenna device according to claim 2, wherein the filter circuit extracts the GPS signal from the received signal of the first inverted L-shaped antenna, wherein