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.