| 摘要 |
The present invention relates to a vehicle mountable satellite antenna as defined in the claims which is operable while the vehicle is in motion. The satellite antenna of the present invention can be installed on top of (or embedded into) the roof of a vehicle. The antenna is capable of providing high gain and a narrow antenna beam for aiming at a satellite direction and enabling broadband communication to vehicle. The present invention provides a vehicle mounted satellite antenna which has low axial ratio, high efficiency and has low grating lobes gain. The vehicle mounted satellite antenna of the present invention provides two simultaneous polarization states. In one embodiment, a hybrid mechanic and electronic steering approach provides a more reasonable cost and performance trade-off. The antenna aiming in the elevation direction is achieved via control of an electronic beamforming network. The antenna is mounted on a rotatable platform under mechanical steering and motion control for aiming the antenna in the azimuth direction. Such approach significantly reduces the complexity and increases the reliability of the mechanical design. The antenna height is compatible to the two-dimensional electronic steering phased-array antenna. Additionally, the number of the electronic processing elements required is considerably reduced from that of the conventional two-dimensional electronic steering phased-array antenna, thereby allowing for low cost and large volume commercial production. The present invention provides electronically generated left, right, up, and down beams for focusing the antenna beam toward the satellite while the vehicle is moving. All of the beams are simultaneously available for use in the motion beam tracking. This provides much faster response and less signal degradation.
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