JP2642889B2 - Mobile Earth Station Antenna Device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a directional antenna for a mobile earth station mounted on a mobile object such as an automobile or a ship in a mobile satellite communication system, and a tracking mechanism therefor.

[0002]

2. Description of the Related Art In the case of a mobile earth station having a directional antenna, it is necessary to move the antenna so as to always compensate for a change in the attitude of the mobile object in order to track the satellite direction.
The following technology has been used as a tracking mechanism of a mobile earth station antenna device. Generally, in order to enable the antenna to be oriented in any direction in the whole sky, two mutually orthogonal axes of rotation, an azimuth axis and an elevation axis (azimuth and elevation, abbreviated Az for short), which are orthogonal in a vertical plane. -E
l) or a combination of two axes (X-Y) orthogonal to each other in a horizontal plane, and each axis is driven by a separate motor.

A feature of the Az-El drive is that, particularly in the case of a mobile earth station used in a mobile object having a small moving range, such as a land vehicle or a ship for inshore waters, the satellite elevation angle is almost constant within the moving range. Therefore, it is possible to reduce the size and weight by driving only the azimuth axis without driving the elevation axis. On the other hand, as a feature of the XY drive, since there is no rotation of the base and the antenna around the azimuth axis, a rotary joint is not required and power can be supplied to the antenna using a normal coaxial cable.

As a tracking control means for always directing the beam direction of the antenna toward the satellite, various sensors measure the azimuth of the traveling direction of the moving body and the inclination angle of the moving body with respect to the horizontal plane, and measure the beam direction of the antenna with respect to the base. Or the method of trially controlling the beam direction so that the intensity of the radio wave from the received satellite is always maximized, or
A technique that combines the above two techniques is used.

[0005]

However, the conventional antenna device described above requires only one drive motor in the Az-El drive when the satellite elevation angle is almost constant and tracking in the elevation direction is not necessary, and the antenna device can be reduced in size. Yes, but the azimuth axis continues to rotate in the same direction for many rotations, and the feeder may be entangled with the axis or cut off. It is not possible to supply power by using a rotary joint that passes high-frequency signals (parts that pass high-frequency signals to the rotating part), so the reliability of the equipment, quality degradation due to high-frequency signal passage loss,
There was a problem such as high price. In XY driving, the antenna does not rotate in the azimuth direction with respect to the base, so a rotary joint is not required. However, even when the satellite elevation angle is almost constant and tracking in the elevation direction is not necessary, always drive both axes. Therefore, two drive motors are required, and there is a problem that the size of the apparatus is increased and the price is high. That is, Az-
In either case of the El drive or the XY drive, it has not been possible to achieve both reduction in size and weight and no use of a rotary joint.

Therefore, the present invention enables a mobile earth station which does not require tracking in the elevation direction to perform satellite tracking in the azimuth direction without using a rotary joint for expensive high-frequency signals and to reduce the size of the apparatus. Lighter weight, lower price,
It is an object of the present invention to provide an antenna device for a mobile earth station which can improve reliability.

In order to solve the above problem, an antenna device for a mobile earth station according to the present invention has a first rotation axis perpendicular to the surface of an antenna base (for example, base 6) located on a virtual horizontal plane. A first rotating member (for example, the rotating unit 2) rotatably connected to the upper side of the antenna base via a first air-core rotating joint (for example, the rotating joint 4), and a satellite elevation angle with respect to a virtual horizontal plane. A second rotary member (for example, a substrate of the antenna 1) rotatably connected to the first rotary member via a second air-core rotary joint (for example, the rotary joint 3) having a second rotary shaft inclined by an angle. ), An antenna (1) that rotates integrally with the second rotation member and has directivity symmetrical about a second rotation axis, the first air-core rotation joint, and the second air-core rotation joint the feed point of the through of the air-core part antenna (8 RF signal line connected to (7)
And a satellite tracking mechanism (for example, a driving mechanism) for turning the beam direction of the antenna to the satellite direction by controlling the rotation of the first rotating member in accordance with the moving direction of the moving body on which the antenna base is installed. Motor 5 and tracking control device),
Was provided.

[0008]

According to the antenna apparatus for a mobile earth station constructed as described above, when the azimuth of the satellite changes with the movement of the moving body, the first turning member is turned by the satellite tracking mechanism, and the first turning member is turned. The second rotation axis of the two-air core rotation joint will be directed toward the satellite. Therefore, the beam direction of the antenna having directivity symmetrical to the second rotation axis also coincides with the satellite direction. Further, the antenna base and the first rotating member are rotatable via a first air core rotating joint, and the first rotating member and the second rotating member are freely rotatable via a second air core rotating joint. And a high frequency signal line passing through the air core portions of the first and second air core rotary joints is supplied to the antenna .
Since the connection is made to the power point, only the second rotating member can be directed toward the satellite without affecting the connection state between the high-frequency signal line and the antenna at the feeding point.

[0009]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of an antenna device for a mobile earth station according to the present invention.

FIG. 1 is a perspective view showing an antenna unit and a rotating unit of a mobile earth station antenna device according to the present invention.

In FIG. 1, reference numeral 1 denotes a disk-shaped antenna unit. A thin disk-shaped antenna such as a microstrip patch antenna is suitable, but any other antenna having an axial symmetry such as a parabolic antenna may be used. In the case of a thin antenna, the antenna element itself can be used as the antenna part, or the antenna element may be attached to a disk-shaped substrate of the antenna part. However,
The polarization of radio waves to which the device of the present invention can be applied is limited to circular polarization, and the antenna element used is also limited to circular polarization.

Reference numeral 2 denotes a rotating portion having a shape obtained by cutting a cylinder obliquely. The rotating portion 2 is connected to the antenna 1 and the base 6 by air-core rotating joints 3 and 4. The rotation joint 4 on the bottom is for rotating around a rotation axis perpendicular to the surface of the base 6, and the rotation joint 3 on the top is around the rotation axis inclined by the satellite elevation angle with respect to the surface of the base 6. It is for rotating. The edge of the bottom surface of the rotating portion 2 is configured to transmit rotation through a drive motor 5 of a base 6 and a gear, and receives power to rotate in a horizontal plane. Although the drive mechanism shown in this figure is configured to directly transmit the rotational force of the drive motor 5 to the rotating part and to rotate the driven part, the drive mechanism is not limited to this. For example, the rotation axis of the drive motor 5 is installed in parallel with the center axis of the rotation part cylinder,
The rotating portion may be indirectly driven and rotated via power transmission means such as a pulley and a belt. Even if the rotation unit 2 rotates, the antenna 1 is connected to the rotation unit 2 by the rotation joint 3 and can be freely moved without necessarily following the rotation of the rotation unit 2. Therefore, for example, if the base and the antenna are connected by feeding power with a normal coaxial cable or the like, the cable suppresses rotation, and thus the antenna 1 is maintained at a constant elevation angle without twisting relative to the base 6. However, it can be directed to any azimuth direction.

The air-core rotary joints 3 and 4 are:
This is for rotating two planes perpendicular to the rotation axis to each other. For example, the inner ring and the outer ring can rotate with each other via a ball bearing, and the inner ring is fixed to the upper plane and the outer ring is set to the lower side. By using a structure that is fixed to a flat surface, a rotary joint having a hollow rotary shaft portion is used.

Reference numeral 5 denotes a drive motor, which rotates the rotary unit 2 by rotating the motor, and turns the antenna 1 to a desired azimuth. That is, the tracking control means (not shown) controls the drive motor 5 so that the beam direction of the antenna 1 is always directed to the satellite, so that the beam direction of the antenna 1 is always changed regardless of the moving direction of the moving body. It functions as a mobile earth station device that can be directed in any direction.

Reference numeral 6 denotes a base, which is mounted on a moving body, for example, a roof of an automobile. In addition, it can be used even in rainy weather by covering the whole with a radome. In the figure, the size is larger than the main reflecting mirror 1 for easy understanding, but it is sufficient if the size is large enough to support the main reflecting mirror.

An inexpensive ordinary coaxial cable can be used for the high-frequency signal line 7 connecting the antenna 1 and the transceiver, and is connected to the transceiver in the vehicle. In the case of a planar antenna, the antenna can be used as it is, and in the case of other shapes, the antenna can be mounted on a disk and used. In any case, the antenna feed point 8 is connected to the high-frequency signal line 7, and the high-frequency signal line 7 is connected to the transceiver through the air core portions of the rotary joints 3 and 4. Since the edge of one edge of the antenna to be used is not fixed depending on the azimuth direction, the antenna to be used needs to have a directional characteristic which is axially symmetric with respect to a virtual line perpendicular to the aperture plane.

Although not shown here, in order to operate as an antenna device for a mobile earth station, a tracking device serving as tracking control means is required inside the moving body. The tracking device uses a received signal from the antenna, a signal from a sensor that detects the direction of travel of the moving object, or both signals, so that the drive beam of the antenna always matches the direction of the satellite. 5 is a device for controlling the device 5.

In addition, in order to communicate as a mobile earth station, it is necessary to have a transmitting / receiving device inside a mobile body. Further, the present apparatus can be used not only as a communication antenna apparatus for both transmission and reception, but also as an antenna apparatus exclusively for reception such as a satellite broadcast receiving apparatus.

It should be noted that the present invention can be easily used not only for bidirectional satellite communication but also for on-vehicle receivers for satellite broadcasting, and can be manufactured in a small, lightweight and inexpensive enough to be mounted on a private car. The effect is extremely large.

[0020]

As described above, according to the antenna apparatus for a mobile earth station according to the present invention, when the azimuth of the satellite changes with the movement of the moving object, the first satellite tracking mechanism is used.
The rotation member is rotated, and the second rotation axis of the second air core rotation joint is directed toward the satellite. Therefore, the beam direction of the antenna having directivity symmetrical to the second rotation axis also coincides with the satellite direction. Further, the antenna base and the first rotating member are rotatable via a first air core rotating joint, and the first rotating member and the second rotating member are freely rotatable via a second air core rotating joint. High-frequency signal passing through the air core portions of the first and second air core rotary joints.
Line a since shall be connected to the feeding point of the antenna, without affecting the connection between the high-frequency signal line and antenna at the feed point, can be directed only the second rotating member in the direction of the satellite.

Therefore, under the condition that the elevation angle is constant,
With only one drive motor, the antenna can direct the beam in an arbitrary azimuthal direction without twisting relative rotation about the first rotation axis with the base. The satellite can be tracked in the azimuth direction without using it, and the size and cost of the device can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a sectional view of the embodiment of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Antenna 2 Rotating part 3 Air core joint 4 Air core joint 5 Drive motor 6 Base 7 High frequency signal line 8 Antenna feeding point

Claims (1)

(57) [Claims] 1. A always beam direction of the antenna includes a tracking mechanism to match the direction of the satellite, mobile earth station communicates with geostationary satellites in a state of being mounted on a mobile object on land or water <br/> antenna In the apparatus, a first rotation rotatably connected to the antenna base upper surface side via a first air-core rotation joint having a first rotation axis perpendicular to a surface of the antenna base positioned on a virtual horizontal plane A first air-core rotary joint having a second rotary axis inclined by an angle of elevation of the satellite with respect to the virtual horizontal plane;
A second rotating member rotatably connected to the rotating member; an antenna that rotates integrally with the second rotating member and has directivity symmetrical to a second rotating shaft; The high frequency signal line connected to the feeding point of the antenna through the air core portions of the air core rotation joint and the second air core rotation joint, 1. An antenna device for a mobile earth station, comprising: a satellite tracking mechanism for turning a beam direction of an antenna toward a satellite direction by controlling rotation of a rotation member.