Antenna with outboard exciter for 3.4-13.25 GHz frequency range

A nonaxisymmetric antenna with a circular aperture 1.1 m in diameter four has rotatable exciters, sharply bent horns tilting 22 deg from the vertical which match frequency bands 4, 6, 8, 11 GHz wide respectively. The performance with ech of the exciters were evaluated including the frequency characteristics of gain, surface utilization factor, and standing-wave ratio under horizontal polarization and vertical polarization. The radiation patterns meet guarantees within and around the main lobe as well as within the side lobes in the far field. The antenna with any exciter has a stable and smooth nonoscillating frequency dependence of gain and surface utilization factor. With the 4 GHz exciter (diameter 70 mm) or with the 6 GHz exciter (diameter 43 mm) there is a small gain but a high interference immunity. With the 8 GHz exciter (diameter 32 mm) or with the 11 GHz exciter (diameter 24 mm) the radiation pattern has very weak side lobes in front and in back. Small size weight make this antenna suitable as etalon for measuring the gain characteristics of large antennas.