Directional antennas are always used in radar system to increase the range and better resolution.
The measure of sharpens and directivity of the radiated beam from the
antenna is, however, dependent on its requirements. If the radar is
being used simply to locate the position of target and not the height
from horizontal, then a sharp beam is radiated in the horizontal
direction to give high azimuth resolutions while sharp beam in the
vertical direction.
In all types of radars, a mechanical motion of the antenna is
accomplished to vary the direction of beam radiated from it. The process
is called antenna scanning. In radars used for navigational purposes,
scanning is performed by rotating the antenna about a vertical axis. In
height-finder radars, scanning consists of rapid rocker motion in the
vertical plane with much lower azimuth scan about a vertical axis.
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