AIRBORNE ANTENNA AND A SYSTEM FOR MECHANICALLY STEERING AN AIRBORNE ANTENNA

摘要

-29-AN AIRBORNE ANTENNA AND ASYSTEM FOR MECHANICALLY STEERING AN AIRBORNE ANTENNAABSTRACT OF THE DISCLOSUREA helical-element antenna as part of a communication systemis mechanically steered with reference to an azimuth axis andan elevation axis within a positioning envelope greater thanhemispherical. The system for mechanically steering thehelical antenna includes a supporting frame having an azimuthmember with a longitudinal axis coinciding with the azimuthaxis around which the antenna rotates. Further, the supportingframe includes an elevation member that is integral with theazimuth member and has a longitudinal axis displaced from theazimuth axis. An interface fitting rotatably mounts theantenna to the elevation member. The supporting frame isrotatably mounted to a pedestal base that has a planeperpendicular to the azimuth axis. To position the antennaabout the azimuth axis, an azimuth steering unit is energizedto rotate the supporting frame 360 degrees around the azimuthaxis. For positioning the antenna about the elevation axis, anelevation steering unit rotates the interface fitting and theantenna through a gear coupling about the elevation axis. Thetotal rotation excursion about the elevation axis is typically180 degrees and points the antenna through a range of elevationangles.7 9 2 9 f