JPH04324382A - Gps receiver for automobile - Google Patents

Abstract

PURPOSE:To arrange a GPS antenna in the compartment of an automobile without obstructing the visual field of a driver while holding good reception characteristics. CONSTITUTION:A microstrip antenna 3 for receiving a horizontal polarized wave is arranged to the dashboard 2 in the compartment of an automobile 1 and a Yagi antenna 5 for receiving a vertical polarized wave is arranged to the rear tray part of the car 1. The outputs of both antennae 3, 5 are added by a signal synthesizer 6 to perform directional diversity reception and good receiving characteristics are obtained even in the compartment low in received electric field intensity. Further, the microstrip antenna 3 or the Yagi antenna 5 is thinly formed easily and, even when the antenna is arranged in the compartment, the visual field of a driven is not obstructed.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to in-vehicle GPS (Global GPS) used in automobile navigation systems.
This relates to a receiving device (Positioning System).

0002

[Prior Art] GPS is a worldwide positioning system planned by the U.S. Department of Defense, and is a system that determines the latitude, longitude, and altitude of a receiving location by receiving signal radio waves from multiple orbiting satellites. be. In order to receive signals from these orbiting satellites, GPS antennas used in automobile navigation systems are omnidirectional,
That is, hemispherical directivity characteristics are required. Further, the reception frequency is 1575.42 MHz, and the reception polarization is right-handed circular polarization. To meet this requirement, one GPS antenna is usually installed in the center of the roof of the vehicle.

[0003] Another reason for installing the GPS antenna outside the vehicle, such as on the roof of the vehicle, is that, like antennas for FM radio receivers, television receivers, and automobile wireless telephones, This is because the received electric field strength inside the vehicle is lower than that outside the vehicle, and there is a risk that the reception characteristics will deteriorate, and furthermore, there is a risk that the driver's view may be obstructed by the antenna inside the vehicle.

0004

[Problem to be solved by the invention] However, as mentioned above, G
If the PS antenna is installed so as to protrude outside the vehicle, problems arise, such as the antenna being easily damaged, the antenna getting in the way when washing the car, and the elegant appearance of the vehicle body being spoiled. The present invention has been made in view of the above points, and it is possible to install a GPS inside a vehicle while maintaining good reception characteristics.
It is an object of the present invention to provide a GPS receiving device for a vehicle in which an antenna can be installed and which does not obstruct the driver's view.

[0005]

[Means for solving the problems] Automobile G according to the present invention
The PS receiver includes a horizontally polarized wave receiving microstrip antenna 3 disposed on a dashboard section 2 inside the vehicle 1, and a vertically polarized wave receiving Yagi antenna 5 disposed on a rear tray section 4 inside the vehicle 1. , both antennas 3,
The present invention is characterized by comprising a signal synthesizer 6 that adds the outputs of the two.

[0006]

[Operation] Directional diversity reception is achieved by adding the outputs of the horizontally polarized wave receiving microstrip antenna 3 placed on the dashboard section 2 and the outputs of the vertically polarized wave receiving Yagi antenna 5 placed on the rear tray section 4 using the signal combiner 6. By doing so, it is possible to achieve a relatively high overall antenna gain and obtain good reception characteristics even in the vehicle interior where the reception field strength is low. In addition, the microstrip antenna 3 for horizontally polarized wave reception and the Yagi antenna 5 for vertically polarized wave reception can be easily made thin, and do not obstruct the driver's view even when installed inside the vehicle interior.

[0007]

EXAMPLES The present invention will be explained in detail by way of examples. Figure 1
indicates the state of the arrangement of the GPS antenna, which is located near the front window on the top surface of the dashboard section 2, which is the frontmost part of the interior of the vehicle 1 (mainly a three-box type passenger car), that is, the front part of the driver's seat. A microstrip antenna 3 for horizontally polarized wave reception is installed at the rearmost part of the vehicle interior, that is, a Yagi antenna 5 for vertically polarized wave reception is installed on the upper surface of a rear tray section 4 near the rear window. . Also, inside the car 1, there is a signal synthesizer 6 electrically connected to both antennas 3 and 5, and a GPS signal synthesizer 6 electrically connected to the signal synthesizer 6.
A receiver 10 is installed. These signal combiners 6 and G
The installation location of the PS receiver 10 is not particularly limited. The signal combiner 6 is a microstrip antenna 3 for receiving horizontally polarized waves.
The output signal from the antenna 5 and the output signal from the vertically polarized wave receiving Yagi antenna 5 are added and synthesized, and for example, a Wilkinson combiner or the like can be used.

[0008] In this way, the signal synthesizer 6 combines signals received at the front and rear parts of the interior of the vehicle 1 to perform directional diversity reception and achieve a relatively high overall antenna gain. However, in the case of thin antennas that are placed close to the ground plate (vehicle body), the main beam generally points toward the zenith and does not exist in a horizontal plane. Under such conditions, if a thin patch antenna for circularly polarized wave reception is used as a GPS antenna and placed at the front and rear of the interior of the vehicle 1, the mutual amplitude correlation coefficient will be 0.83, which generally indicates directional diversity. This is larger than 0.6, which is said to be effective, and is not suitable for directional diversity reception. Therefore, in the present invention, in order to receive circularly polarized GPS signals using the directional diversity method, the microstrip antenna 3 for horizontally polarized wave reception, which is a linearly polarized wave reception antenna that can obtain a low mutual amplitude correlation, and the vertically polarized A wave receiving Yagi antenna 5 is used at the front and rear of the vehicle interior of the automobile 1, so that directional diversity reception can be performed effectively. When a circularly polarized wave signal is received by a linearly polarized wave receiving antenna, the gain decreases by 3 dB, but by using a directional antenna with a gain of 3 dB or more as each linearly polarized wave receiving antenna, the decrease in reception sensitivity is avoided. be able to. For this reason, the present invention uses a horizontally polarized wave receiving microstrip antenna 3 and a vertically polarized wave receiving Yagi antenna 5 as linearly polarized wave receiving antennas.

FIG. 2 shows the directional characteristics (
FIG. 3 shows the directivity characteristics (only the vertical polarization component) of the three-element Yagi antenna 5 for vertical polarization reception installed in the rear tray section 4. The mutual amplitude correlation coefficient of the reception level with respect to the signal arrival angle of the directional characteristics of both antennas 3 and 5 is found to be 0.47, which is smaller than the above-mentioned 0.6, so that a directional diversity effect is obtained. be able to. Both antennas 5,
FIG. 4 shows the directional characteristics (vertical polarization component only) after the synthesis of 6. Note that the linearly polarized wave receiving Yagi antenna 5 is not limited to a three-element one. The Yagi antenna can be easily made thin by forming it into a known shortened Yagi antenna structure, and the horizontally polarized wave receiving microstrip antenna 3 is generally made thin using a printed wiring board or the like. Therefore, by horizontally arranging the horizontally polarized wave receiving microstrip antenna 3 and the vertically polarized wave receiving Yagi antenna 5 on the upper surface of the dashboard section 2 and rear tray section 4, the front window can be This prevents the antennas 3 and 5 from obstructing the front view through the rear window and the rear view through the rear window.

0010

Effects of the Invention As described above, the present invention provides a horizontally polarized wave receiving microstrip antenna disposed on the dashboard of an automobile, and a vertically polarized wave receiving microstrip antenna disposed on a rear tray of an automobile. Since it is equipped with an antenna and a signal combiner that adds the outputs of both antennas, the output signals of the horizontally polarized wave receiving microstrip antenna on the dashboard and the vertically polarized wave receiving Yagi antenna on the rear tray are combined into the signal combiner. It is possible to perform directional diversity reception by combining with
The GPS antenna can be installed inside the vehicle while maintaining good reception characteristics. Furthermore, the microstrip antenna for horizontally polarized wave reception and the Yagi antenna for vertically polarized wave reception can be easily formed to be thin, so that they do not obstruct the driver's view even when installed indoors.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of an embodiment of the present invention.

FIG. 2 is a diagram showing antenna directivity characteristics of a horizontally polarized wave receiving microstrip antenna installed on the dashboard section of the same as above.

FIG. 3 is a diagram showing antenna directivity characteristics of a Yagi antenna for vertically polarized wave reception installed in the rear tray section of the same as above.

FIG. 4 is a diagram showing the combined antenna directivity characteristics of both the antennas of the dashboard part and the rear tray part.

[Explanation of symbols]

1 Car 2 Dashboard section 3 Microstrip antenna for horizontally polarized wave reception 4
Rear tray section 5 Yagi antenna for vertical polarization reception 6 Signal combiner

Claims (1)

[Claims] [Claim 1] A microstrip antenna for horizontally polarized wave reception placed in a dashboard part of a vehicle interior of an automobile, a Yagi antenna for vertically polarized wave reception placed in a rear tray part of a vehicle interior of a vehicle, and outputs of both of the above antennas. What is claimed is: 1. A GPS receiver for an automobile, comprising: a signal synthesizer for adding .