JPH08162843A - Microstrip antenna system and reception method using on-vehicle microstrip antenna - Google Patents

Abstract

PURPOSE: To improve the reception performance by eliminating a deviation in a resonance frequency of a microstrip antenna element even at a position in a compartment of an automobile apart sufficiently from a glass pane or even when a radome is sticked onto the glass pane. CONSTITUTION: A radome 16 is arranged in front of a microstrip antenna element 12 in a radiation direction of an electromagnetic wave and then fixed and a dielectric member 17 is selectively attached or detached to cover the radome 16. When the antenna is in use while being a part sufficiently from a glass pane, the dielectric member 17 is covered onto he radome 16 thereby making the resonance frequency of the microstrip antenna element 12 with, e.g. a frequency of a signal from a GPS satellite to be received. Furthermore, when the dielectric member 17 is removed and the radome is sticked onto a glass pane, the resonance frequency is coincident with a frequency to be received.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a GPS (Global Positionin) which is mounted on an automobile to measure the current position of the vehicle.
The present invention relates to a microstrip antenna device suitable for being installed and used in a vehicle interior for a g System), and a receiving method using the onboard microstrip antenna device.

[0002]

2. Description of the Related Art Conventionally, as a navigation device for a vehicle, a device using GPS for receiving the transmitted radio waves of a plurality of artificial satellites and positioning the current position of the vehicle is well known. In this device, a GPS antenna device for receiving radio waves transmitted from a GPS satellite is a micro-electrode in which a radiation electrode is provided on the surface of a dielectric substrate such as Teflon (trade name) or other low dielectric loss synthetic resin or ceramic. Strip patch antenna elements are often used.

As a configuration for installing the GPS antenna device in a vehicle, one of a type to be installed outdoors of the vehicle,
There are types that are installed inside the vehicle. The outdoor installation type is usually used on the roof of the vehicle, the upper part of the trunk, etc.
Since it can be installed in a place with a good view of the sky, the number of GPS satellites that can be received increases, and the positioning accuracy of the vehicle increases. On the other hand, since it is installed outside the vehicle, structural consideration must be taken so that it will not fall off when it is installed on the vehicle, and a structure such as waterproofing against rain etc. is required.

On the other hand, the indoor installation type is
Although a relatively simple structure is required for mounting and waterproofing,
GPS on the dashboard or the rear tray inside the vehicle
Even if it is installed in a place where the conditions for receiving satellites are relatively good, GPS can still be received because the roof of the vehicle blocks the sky.
Since the number of satellites is reduced, the positioning accuracy of the vehicle may be deteriorated or positioning may not be possible. For this reason, conventionally, two GPS antenna devices are installed in the front and rear of a vehicle cabin such as a dashboard and a rear tray to receive by a diversity method, or signals of two antennas are combined to generate a GPS satellite signal. A configuration is adopted in which the number of receptions is increased.

In 1993, a total of 24 GPS satellites were prepared, and if they were installed in a vehicle room in a place with good visibility with respect to the sky, one antenna would be able to receive a relatively large number of GPS satellites. However, unless the place is in a bad condition, the positioning of the vehicle is not so hindered.

When the GPS antenna device is installed in the vehicle compartment, in addition to being installed on the dashboard or the rear tray, the GPS antenna device is installed on a glass surface such as a rear window with a relatively gentle inclination so as to have a clear view to the sky. It can also be installed from the inside.

A typical GPS antenna device 5 is shown in FIG.
0 is shown. Microstrip antenna element 1
The output of is amplified by an amplifier circuit 2 and is derived, and a synthetic resin radome 4 covering the microstrip antenna element 1 is fixed to the cabinet 3. Thus, the GPS antenna device 5 is configured.

As shown in FIG. 11, the GPS antenna device 5 may be used in a state of being attached to a glass plate 6 such as a rear window of an automobile.

FIG. 12 is a graph showing a return loss characteristic which is a reflection loss of the GPS antenna device 5 shown in FIGS. 10 and 11. A line 7 shows the characteristics when the GPS antenna device 5 is used in a position where the GPS antenna device 5 is charged and separated from the glass plate 6 in the vehicle interior as shown in FIG. The resonance frequency of the GPS antenna 5 in this state is 1575.42 MHz, and the GPS satellite signal can be resonated and received. On the other hand, as shown in FIG. 11, the GPS antenna 5 is attached to the glass plate 6.
When the glass plate 6 is attached, the characteristics shown by the line 8 in FIG. 12 are obtained when the thickness of the glass plate 6 is 4 mm.
In the state of FIG. 11, the resonance frequency of the microstrip antenna element 1 is from 1575.42 MHz to about 15
It can be seen that it is lowered by MHz. About 15
The deviation of MHz is that the frequency band of the signal from the GPS satellite is about 2 MHz, and the GPS antenna device 5
Considering the frequency band of, it is quite large. G like this
When the PS antenna 5 is attached to the glass plate 6, its return loss increases and the antenna gain decreases.

As can be seen from the above, when the GPS antenna device is installed on the dashboard or the rear tray, that is, when only the radome 4 is present in front of the antenna element 1 and when it is installed on the glass plate 6, that is, Since the resonance frequency of the antenna element 1 is different from the case where the radome 4 and the glass plate 6 are present in front of the antenna element 1, one antenna device for GPS is compatible with both installation methods. There is a problem such as deterioration of reception performance due to the shift of the resonance frequency of the.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to mount a microstrip antenna device on a vehicle so that the resonance frequency can be used in accordance with the frequency to be received regardless of the installation location. It is to provide a receiving method to be used.

[0012]

According to the present invention, there is provided a microstrip antenna element, and a dielectric member selectively detachably provided in front of a radiation direction of an electromagnetic wave of the microstrip antenna element. It is a strip antenna device. Further, according to the present invention, the radome is fixed to the microstrip antenna element, the dielectric member is removably provided so as to be stacked on the radome, and the relative dielectric constant of the radome is arranged close to the dielectric plate. At this time, the resonance frequency of the microstrip antenna element is selected so as to match the frequency to be received, and when the radome is arranged apart from the relative dielectric plate, the dielectric member is mounted and the relative dielectric member The relative permittivity is selected such that the resonance frequency of the microstrip antenna element matches the frequency to be received with the radome and the relative dielectric member arranged in front of the microstrip antenna element. . Further, the present invention provides an on-vehicle microstrip antenna device, which comprises a microstrip antenna element and a dielectric which is selectively detachably provided in front of a radiation direction of electromagnetic waves of the microstrip antenna element. When a vehicle-mounted microstrip antenna device including a body member is arranged close to and away from a dielectric plate of an automobile, the dielectric material is arranged so that the resonance frequency of the vehicle-mounted microstrip antenna device matches the frequency to be received. It is a receiving method using a vehicle-mounted microstrip antenna device characterized by selecting a relative permittivity of a member.

[0013]

According to the present invention, a dielectric member is selectively removably provided in front of a radiation direction of an electromagnetic wave of a microstrip antenna element that receives a signal from a GPS satellite, for example. Therefore, for example, when the present microstrip antenna device is used at a position sufficiently separated from a dielectric plate such as a glass plate or a synthetic resin plate that closes the opening of the automobile, the dielectric member is used. The resonance frequency of the microstrip antenna element is made to match the frequency to be received by mounting or using a dielectric member having a large relative dielectric constant. Further, when the microstrip antenna device of the present case is used in the vicinity of a dielectric plate such as a glass plate or a synthetic resin plate, for example, being attached and used, the dielectric member is removed or a dielectric member having a small relative dielectric constant is used. , Thereby matching the resonant frequency of the microstrip antenna element to the frequency to be received.

Further, according to the invention, a radome is fixed to the microstrip antenna element, and the dielectric member is removably provided so as to be superposed on the radome.
For example, a dielectric member is provided outside the radome, that is, on the side opposite to the microstrip antenna element, or a dielectric member is arranged between the microstrip antenna element and the radome. When the microstrip antenna device of the present invention is used in a vehicle interior at a position distant from the vehicle, the resonance frequency of the microstrip antenna element can be matched with the frequency to be received, and the microstrip antenna device of the present invention can be used as a dielectric for an automobile. When used by being attached to a plate, for example, the dielectric member is removed, and the resonance frequency is made to match the frequency to be received with the dielectric plate and the radome arranged in front of the microstrip antenna element. You can

[0015]

1 is a sectional view of a vehicle-mounted microstrip antenna device 11 according to an embodiment of the present invention. The microstrip antenna element 12 is provided on a substrate 13, and the substrate 13 is fixed to a cabinet 14 made of synthetic resin. The output of the microstrip antenna element 12 is amplified and derived by the low noise amplifier circuit 15 provided on the substrate 13. A radome 16 is fixed to the cabinet 14 so as to cover the microstrip antenna element 12 in front of the electromagnetic radiation in the radiation direction (upper side in FIG. 1). The radome 16 is formed in a hat shape.

In order to change and correct the resonance frequency of the microstrip antenna element 12, a cap-shaped dielectric member 17 is selectively and detachably provided on the cabinet 14 so as to cover the radome 16.

FIG. 2 is a perspective view of the microstrip antenna element 12 shown in FIG. 1, and FIG. 3 is a vertical sectional view thereof. This microstrip antenna element 12
Is a so-called rectangular microstrip patch antenna, in which the ground electrode 19 is disposed on the lower surface of the plate-shaped dielectric 18 in FIGS. 2 and 3, and the rectangular radiation electrode 2 is disposed on the upper surface.
0 is provided. A feeding line 21 is connected to the radiation electrode 20 and a feeding point F. The resonance frequency of the microstrip antenna element 12 is represented by Expression 1.

[0018]

[Equation 1]

Here, εr is the relative permittivity, C0 is the speed of light, the thickness of the dielectric 18 is h, and the radiation electrode 20 is
It has width a × length b, and the dielectric 18 also has width W2 × length W1.
Then, aeff in Equation 1 is as in Equation 2, and εb in Equation 2 is as in Equation 3.

[0020]

[Equation 2]

FIG. 4 is a perspective view showing a microstrip antenna element of another embodiment of the present invention which replaces the microstrip antenna element 12 shown in FIGS. The microstrip antenna element 12 shown in FIG. 4 is a so-called modified microstrip patch antenna, and the portions corresponding to those in the above-described embodiment are designated by the same reference numerals. The resonance frequency of the circular microstrip patch antenna shown in FIG. 4 is shown in Expression 4.

[0022]

(Equation 3)

[0023]

[Equation 4]

Here, the radius of the disk-shaped radiation electrode 20 is set to a1.
And

The dielectric 18 of the microstrip antenna element 12 in FIGS. 2 to 4 may be a fluorocarbon resin such as polycarbonate or Teflon (trade name), and its dielectric constant εr is 2.55, for example. It may be.

From the above equations 1 and 4, it is understood that when the relative permittivity εr of the dielectric 18 changes and the relative permittivity εr increases, for example, the resonance frequency fr decreases. Further, according to the experiments by the inventor of the present invention, it has been confirmed by experiments that the resonance frequency fr becomes low when a dielectric plate such as a glass plate or a synthetic resin plate is placed in the immediate vicinity of the microstrip antenna device 11. It was

FIG. 5 is a sectional view showing a part of a GPS receiving system showing a state in which the on-vehicle microstrip antenna device of the embodiment of the present invention shown in FIGS. 1 to 4 is mounted on an automobile 22. The microstrip antenna device 11 according to the present invention is arranged on the opening of the vehicle body of the automobile 22, for example, on the dashboard 24 which is sufficiently separated from the glass plate 23 of the rear window in this embodiment. The signals received by the GPS satellites from the microstrip antenna device 11 are transmitted from the line 21 (see FIG. 3) to the line 2
Then, it is given to the positioning device 26 of the automobile. The glass plate 23 has a relatively high relative permittivity, and when the microstrip antenna device 11 is arranged at a position sufficiently distant from the glass plate 23, the dielectric member 17 is arranged as shown in FIG.
The resonance frequency of the microstrip antenna element 12 is thus determined to be 1575.42 MHz from GPS satellites, as shown in FIG.

The radome 16 and the dielectric member 17 are preferably made of a synthetic resin material having a low dielectric loss and a high dielectric constant, such as PPO resin (polyphenylene oxide resin), or a dielectric constant of about 10 or so. It may be alumina Al ₂ O ₃ or the like.

The state in which the microstrip antenna device 11 is used by being attached to the glass plate 23 of the automobile 22 is shown in FIG. At this time, the dielectric member 17 of the microstrip antenna device 11 is removed, and the radome 16 is removed.
Are attached to the surface of the glass plate 23 on the indoor side by an adhesive or the like. As a result, the resonance frequency of the microstrip antenna element 12 is matched with the frequency to be received.

In the microstrip antenna device 11 shown in FIG. 1 described above, a radome 16 is provided in front of the microstrip antenna element 12 (upper part in FIG. 1), and the resonance frequency of the microstrip antenna element 12 is the radome. It is affected by the relative permittivity of 16 materials. That is, in a dielectric having a relative permittivity of more than 1, the wavelength of the electromagnetic wave is shortened as compared with the free space. Therefore, even when the dielectric is present in the immediate vicinity of the microstrip antenna element 12, the electromagnetic wave is compared with the free space. Is shortened, so that the resonance frequency fr of the microstrip antenna element 12 is lowered as described above. The present microstrip antenna device 11 is designed in consideration of the change in the resonance frequency due to the influence of the relative permittivity of the radome 16 in front of the microstrip antenna element 12.
In order to prevent the resonance frequency of the microstrip antenna element 12 from being lowered when it is attached to the glass plate 23 as shown in FIG. In this state in which the dielectric member 17 is removed and the radome 16 is attached to the rear window glass plate 23, the relative dielectric constant of the radome 16 is adjusted so that the resonance frequency of the microstrip antenna element 12 becomes 1575.42 MHz. The ratio and the thickness of the front of the microstrip antenna element 12 are appropriately selected, and the resonance frequency of the microstrip antenna element 12 is 157 as described above when the microstrip antenna device 11 is removed from the glass plate 23.
A dielectric member 1 having a high dielectric constant of 5.42 MHz
7 is additionally mounted on the radome 16.

FIG. 7 is a sectional view of a vehicle-mounted microstrip antenna device 27 according to another embodiment of the present invention. This embodiment is similar to the previous embodiment, and corresponding parts bear the same reference numerals. In this embodiment, it should be noted that the storage space 30 is provided between the top 29 of the radome 28 fixed to the cabinet 14 and the microstrip antenna element 12.
Is formed. A flat plate-shaped dielectric member 31 is selectively and detachably provided in the storage space 30. Other configurations are the same as those in the above-mentioned embodiment. In the state of FIG. 7 in which the dielectric member 31 is mounted in the storage space 30, the above-mentioned FIG.
Similarly to the glass plate 23 on the rear tray 24 of the automobile 22
Is used at a position sufficiently far away from the antenna to match the resonance frequency of the microstrip antenna element 12 to the frequency to be received.

When the microstrip antenna device 27 shown in FIG. 7 is used by being attached to the glass plate 23 of the rear window of the automobile 22 as shown in FIG. 8, the dielectric member 31 is removed from the storage space 30. To be done.
As the dielectric member 31, for example, alumina Al ₂ O ₃ having a dielectric constant of about 10 can be used.

FIG. 9 is a sectional view of a vehicle-mounted microstrip antenna device 32 according to another embodiment of the present invention. This embodiment is similar to the previous embodiment, and corresponding parts bear the same reference numerals. It should be noted that, in this embodiment, the cabinet 14 is provided with a plurality of cap-shaped dielectric members 33, 34 that are selectively detachable and replaceable. These dielectric members 33 and 34 have a structure similar to that of the radome 16 described above. When the vehicle-mounted microstrip antenna device 32 shown in FIG. 9 is used while being sufficiently separated from the glass plate 23 of the automobile 22 as shown in FIG. 5, the dielectric member 33 has a relatively high relative dielectric constant. When it is made of a material having a specific ratio and is used by being attached to the glass plate 23 as shown in FIGS. 6 and 8, the dielectric member 34 is exchanged, and the dielectric member 34 has a relatively small relative dielectric constant. Have a rate. In this way, the resonance frequency of the microstrip antenna element 12 can be matched with the frequency to be received, regardless of the use state.
In this way, the resonance frequency of the microstrip antenna element 12 is always corrected and kept at the frequency of the signal from the GPS satellite, and therefore, the calculation operation such as positioning can be accurately performed without deteriorating the reception performance.

The on-vehicle microstrip antenna device 11, 27, 32 of the present invention can be easily attached to a glass plate such as a front window or a side window for closing an opening of an automobile or a synthetic resin plate. It can be attached and used. The present invention can be used not only for receiving signals from GPS satellites, but also in a wide variety of other applications.

The present invention can be used not only for being mounted on an automobile but also for example in a building, and the present invention can be implemented in other applications. The invention can be used not only for reception, but also for transmission.

[0036]

According to the present invention, since the dielectric member is selectively attached to and detached from the front of the microstrip antenna element in the electromagnetic wave radiation direction, the opening of the automobile is closed, for example, in the interior of the automobile. It is possible to make the resonance frequency of the microstrip antenna element match the frequency to be received even at a position sufficiently distant from the glass plate or synthetic resin plate to be used, or in a state where the microstrip antenna element is used by being attached to the dielectric plate. This is easily possible, whereby the return loss of the present microstrip antenna device can be reduced, the antenna gain can be improved, and the deterioration of the reception performance due to the shift of the resonance frequency can be prevented.

Further, according to the present invention, the radome is fixed to the microstrip antenna element, and the dielectric member is removably provided on the radome so that the microstrip antenna element is protected and damaged by the radome. Never.

[Brief description of drawings]

FIG. 1 is a sectional view of a vehicle-mounted microstrip antenna device according to an embodiment of the present invention.

FIG. 2 is a perspective view of the microstrip antenna element 12 shown in FIG.

3 is a vertical cross-sectional view of the microstrip antenna element 12 shown in FIG.

FIG. 4 is a perspective view of a microstrip antenna element 12 according to another embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a state in which the on-vehicle microstrip antenna device 11 is arranged and used on a rear tray 24 which is sufficiently separated from a glass plate 23 of a rear window of an automobile.

FIG. 6 is a cross-sectional view showing a state in which the microstrip antenna device 11 is used by being attached to the surface on the indoor side of the glass plate 23 in the rear window of the automobile 22.

FIG. 7 is a sectional view of a vehicle-mounted microstrip antenna device 27 according to another embodiment of the present invention.

8 is a perspective view of the vehicle-mounted microstrip antenna device 27 shown in FIG.
3 is a cross-sectional view showing a state in which the device is attached to No. 3 and used.

FIG. 9 is a sectional view of a vehicle-mounted microstrip antenna device 32 according to still another embodiment of the present invention.

FIG. 10 is a sectional view of the prior art.

11 is a cross-sectional view showing a usage state in which the on-vehicle microstrip antenna device 5 shown in FIG. 10 is attached to a glass plate 6 of an automobile.

FIG. 12 is a graph showing a return loss characteristic in each usage state of the prior art shown in FIGS. 10 and 11.

[Explanation of symbols]

11, 27, 32 In-vehicle microstrip antenna device 12 Microstrip antenna element 13 Substrate 14 Synthetic resin cabinet 15 Low noise amplification circuit 16, 28 Radome 17, 31, 33, 34 Dielectric material 18 Dielectric 19 Ground electrode 20 Radiation Electrode 21 Feed line 22 Automobile 23 Rear window glass plate 24 Rear tray F Feed point

Claims (3)

[Claims] 1. A microstrip antenna device comprising: a microstrip antenna element; and a dielectric member that is selectively detachably provided in front of a radiation direction of electromagnetic waves of the microstrip antenna element. 2. A radome is fixed to a microstrip antenna element, a dielectric member is removably provided so as to overlap the radome, and the relative dielectric constant of the radome is such that the radome is arranged close to the dielectric plate. At this time, the resonance frequency of the microstrip antenna element is selected so as to match the frequency to be received, and when the radome is arranged apart from the relative dielectric plate, the dielectric member is mounted and the relative dielectric member The relative permittivity is
2. The resonance frequency of the microstrip antenna element is selected so as to match the frequency to be received with the radome and the relative dielectric member arranged in front of the microstrip antenna element. Microstrip antenna device. 3. A vehicle-mounted microstrip antenna device is prepared, and the vehicle-mounted microstrip antenna device is provided with a microstrip antenna element and a dielectric that is selectively detachably provided in front of a radiation direction of electromagnetic waves of the microstrip antenna element. When the in-vehicle microstrip antenna device including the body member is arranged close to and away from the dielectric plate of the automobile, the dielectric material is arranged so that the resonance frequency of the in-vehicle microstrip antenna device matches the frequency to be received. A receiving method using a vehicle-mounted microstrip antenna device, characterized in that a relative dielectric constant of a member is selected.