JPS5912144B2 - In-vehicle radar device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vehicle-mounted radar device, and particularly to a vehicle-mounted radar device that can obtain a sharp beam and eliminate radio wave interference between radars.

Various in-vehicle radar devices have been proposed to be mounted on a car to check the distance between vehicles or detect obstacles, but such radars include Mills, Cross, Antenna (M
i II's Cross Antenna) is preferable because it has a direction setting function, ventilation, etc. By the way, when many cars are equipped with this type of radar device, two opposing cars are close to each other on a straight road. When driving on a curved road or driving on a curved road, radio wave interference occurs between each radar, which can degrade the detection performance of the radar or cause the radar to malfunction, leading to a major accident. There is a fear.

The present invention has been made in view of the above points, and provides an in-vehicle radar device equipped with a novel Mills, Cross, and antenna in which the plane of polarization of the antenna is inclined.

The in-vehicle radar device of the present invention has two slot-shaped antennas arranged in a figure-7 shape at the front or rear of the vehicle so that their radiation patterns are orthogonal to each other, and one of these antennas is used for transmission. One antenna is used as one antenna, and the other is used as a receiving antenna. Preferred embodiments thereof will be described in detail below with reference to the drawings.

First, to explain the principle of the Mills, Cross, and Cross antenna, as shown in Figure 1, it consists of an antenna A in the horizontal direction (x) and an antenna B in the vertical direction (y). On the other hand, the radiation pattern by antenna A is a1, and the radiation pattern by antenna B is b, so the combined pattern forms a sharp pencil beam in two axial directions as shown in C.

FIG. 2 is a front view of an automobile to which the antenna of the present invention is attached.
Two slot-shaped antennas A and B are each arranged in a V-shape at an angle of 45 degrees with respect to the vertical direction.

These slot-shaped antennas are, for example, longitudinal antennas with A used for transmission.

Shunt (Longitudinal 5hunt)
, a slot array antenna is used, and an edge, shunt (Edge 5hunt), and slot array antenna are used with B used for reception.

As is well known, the former has a radiated electric field direction perpendicular to the array axis, and the latter has a radiated electric field direction horizontal to the array axis.
If the device is a radar device, the electric field directions will be in the same direction and it will function as a radar device.

Furthermore, the radiation patterns from the two antennas A and B are 45° in the vertical direction, as shown in FIG.
° Pencil, which will be orthogonal to each other in a slanted shape
form a beam.

Since this beam axis C is aligned with the direction of travel of the car, only obstacles ahead that are within the range of this beam C, that is, only objects that are likely to collide, are detected, making this method highly practical. .

Also, as mentioned above, the polarization plane of all antennas is 45°.
By providing an inclination, the antennas of the opposing party have polarization planes of 90° to each other, and therefore, radio wave interference between radars is almost eliminated.

Although not shown, power is supplied to the two antennas from the base end side of the V-shaped arrangement.

FIG. 4 shows another embodiment of the present invention, in which the aperture surfaces of the two slot antennas A and B are opposed to the respective reflecting surfaces of the cylindrical parabolic reflection fields 11 and 12, so that a so-called cylindrical antenna is arranged in a V-shape. It constitutes a parabolic antenna.

According to this antenna shape, each antenna can form a sharp fan beam with orthogonal radiation patterns, thereby further improving radar detection performance.

In addition, in FIG. 4, a power feeding section 13 of each antenna is provided at the base end of the V-shaped arrangement, and an oscillator 14 integrated therein is provided.
By installing a mixer 15 and the like to configure a transmitter/receiver and directly connecting the transmitter/receiver to the antenna, a compact radar device without a feed line can be provided.

As is clear from the above description, according to the in-vehicle radar device of the present invention, the long axes of the two antennas are arranged in a V-shape so that the plane of polarization of the antennas is inclined, and the long axes of the two antennas are arranged in a V-shape. Since the radiation patterns are orthogonal to each other to form pencil beams, it is possible to completely eliminate radio wave interference between radars, and since it has an azimuth setting function, it is possible to reliably detect obstacles in front.

Since the antenna has a roughly V-shaped arrangement, it does not impair the exterior beauty of the automobile, and since it has good ventilation, there is no risk of impairing the engine cooling effect.

The combined shape of the two antennas of the present invention is not limited to the above-mentioned arrangement in a V-shape opening from the road surface, but may also be arranged, for example, in an inverted ■-shape opening toward the road surface.

It is also possible to form a sharp fan beam by having the aperture of the antenna face the radio lens, and the antenna is not limited to a slot but may be of a dipole type.

[Brief explanation of the drawing]

Fig. 1 is a diagram for explaining the principle of the Mills, Cross, antenna, Fig. 2 is a front view of the radar device according to the present invention attached to the front grill of a car, and Fig. 3 is an explanatory diagram of its radiation characteristics. FIG. 4 is a diagram showing another embodiment of the present invention. In the figure, A and B are slot antennas, 11 and 1
2 is a circular reflector, 13 is a power feeding section, and 14 and 15 are an integrated circuit oscillator and mixer, respectively.

Claims (1)

[Claims] 1. An antenna whose radiation characteristics both form a fan beam and whose electric field direction is along the long axis and an antenna whose electric field direction is perpendicular to the long axis is used to calculate the radiation of these antennas. A vehicle-mounted radar device characterized in that the patterns are arranged in a V-shape so that they are orthogonal to each other, and one of these antennas is used as a transmitting antenna and the other is used as a receiving antenna. 2 The above two antennas are edge and shunt. The vehicle-mounted radar device according to claim 1, comprising a slot array antenna, a longitudinal shunt, and a slot array antenna. 3. The in-vehicle radar device according to claim 1 or 2, characterized in that the aperture surfaces of the two antennas are opposed to a cylindrical parabolic reflector to form a reflection type antenna arranged in a V-shape. . 4. The vehicle-mounted radar device according to any one of claims 1 to 3, wherein power is supplied to the two antennas from the base end side of the V-shaped arrangement.