(57) A shaped beam antenna comprises an array antenna having a planar surface on which
a plurality of radiating elements are arranged, and a main reflector disposed behind
with respect to the radiating direction of the array antenna. The main reflector comprises
a plurality of partial cylindrical or planar reflector segments. Where Cartesian coordinates
is assumed having an origin in the center of the planar surface of the array antenna,
an X-axis extending in a vertical center axis of the array antenna, a Z-axis extending
in a direction perpendicular to the planar surface through the origin, and a Y-axis,
extending in a direction perpendicular to the X- and Z-axes through the origin, the
shaped beam antenna is characterized in that the longitudinal axis of each reflector
segments is in parallel with the X-axis, the main reflector is symmetrical with respect
to the X-Z plane and formed convex in a negative direction of the Z-axis, and each
radiating element is disposed so that its excitation amplitude is symmetrical with
respect to the Y-Z plane and its excitation phase is antisymmetrical with respect
to the Y-Z plane, whereby a radiation beam formed by the main reflector is symmetrical
with respect to the Z-axis on the Y-Z plane and is asymmetrical with respect to the
Z-axis on said X-Z plane. Thus, with this antenna, a good beam shaping performance
and an excellent cross polarization discrimination can be obtained.
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