Japan Radio Co., Ltd.

Kouichi Eguchi

Tsuguya Inoie

A tracking array antenna system is provided. When a signal from the target is received normally, control mode of an AZ axis and an electronic XEL axis is changed over according to whether or not a moving platform is inclined about the XEL axis for detecting inclination of the moving platform. When the moving platform is not inclined, beam-switch (BSW) about the electronic XEL axis is performed, and the beam-switch tracking (BST) about the AZ axis using the result with an angular rate feedback (ARFB) is performed. When the moving platform is inclined, zero rate control (ZRC) about the AZ axis and BST about the electronic XEL axis are performed. In this way, tracking and stabilization are performed without not only the gimbal-lock but also the use of a gyrocompass.

Tracking array antenna system

An array antenna system is provided with a function for tracking a target. The system captures the target by first carrying out search control immediately after a power supply is turned on. After capturing the target, the system performs tracking control using a beam switch controller about an azimuth. An output of a rate sensor is filtered by a high-pass filter and then reflected on a tracking signal for the tracking control. It is possible to keep an angular rate of the array antenna around an azimuth axis to nearly 0 even while no signals can be received from the target. Even when signals can be received from the target, a control system is stabilized by feedback of the angular rate.

A stabilized antenna system is installed on a moving platform such as a ship to track a communication satellite. The antenna system examply employs either X1-Y-X2 or Y1-X-Y2 antenna mount. Rolling and pitching of the moving platform are offset by mechanically steering outside and intermediate axes, X1 and X, or Y1 and Y axes. The innermost axis is electronically steered to prevent instability which is caused by the mechanical steering, thereby improving reliability of the antenna system. The frame for rotatable supporting the array antenna is also supported by the radome rotatably. Further, the access hutch for maintainance is opened at the center of the radome and just below the array antenna.

Stabilized antenna system

A stabilized antenna system. An inclination angle detector is mounted on an AZ frame and detects an inclination angle around an elevation, and the elevation of the antenna is controlled by a successive addition of the detected inclination angle to simplify control algorithm. Furthermore, the inclination angle detector includes a reciprocal combination filter for combining outputs of an inclinometer and a rate sensor. The reciprocal combination filter includes two reciprocal filters, and parameters of the reciprocal filters are adaptively controlled depending on frequency and amplitude of the inclination to ensure the reciprocity in a necessary frequency range.

Stabilized ship antenna system for satellite communication

An array antenna can control directions of beams by phase-shifting signals received and/or transmitted by a plurality of antenna elements. When the antenna elements are arranged two-dimensionally, sidelobes and beamwidth are determined according a distance between two adjacent antenna element columns. The distance between the adjacent columns can be reduced by arranging the antenna elements in a staggered manner, thereby suppressing the sidelobes, and enlarging the width of beams around an XEL axis. A stabilized antenna system controls the direction of the array antenna and beam directivity by compensating for inclination of a moving platform, so that the array antenna can always track a satellite reliably.

Array antenna and stabilized antenna system

In an antenna support device including a horizontal stabilized platform supported by two orthogonal corrective shafts and provided with a flywheel driven by a motor whose spin vector is directed at right angles to the plane of the platform, one of the corrective shafts is actively controlled in response to a tilt of the platform about the other corrective shaft, while the other corrective shaft is actively controlled in response to a tilt of the platform about said one corrective shaft, and axes of an azimuthal shaft directed at right angles to the plane of the platform for supporting an antenna from the platform and the two corrective shafts intersect with each other substantially at one point, whereby torques induced by gravity and linear acceleration may be substantially counter-balanced within almost all the movable ranges about the two corrective shafts.

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Mitaka, Japan

Kouichi Eguchi