Airborne antenna and a system for mechanically steering an airborne antenna

摘要

A helical-element antenna as part of a communication system is mechanically steered with reference to an azimuth axis and an elevation axis within a positioning envelope greater than hemispherical. The system for mechanically steering the helical antenna includes a supporting frame having an azimuth member with a longitudinal axis coinciding with the azimuth axis around which the antenna rotates. Further, the supporting frame includes an elevation member that is integral with the azimuth member and has a longitudinal axis displaced from the azimuth axis. An interface fitting rotatably mounts the antenna to the elevation member. The supporting frame is rotatably mounted to a pedestal base that has a plane perpendicular to the azimuth axis. To position the antenna about the azimuth axis, an azimuth steering unit is energized to rotate the supporting frame 360 degrees around the azimuth axis. For positioning the antenna about the elevation axis, an elevation steering unit rotates the interface fitting and the antenna through a gear coupling about the elevation axis. The total rotation excursion about the elevation axis is typically 180 degrees and points the antenna through a range of elevation angles.