Design, manufacture and test of an electrical model of a shaped beam antenna for a maritime satellite

Optimum beamshapes are defined which can be obtained at the specified operating frequencies with 2 m aperture. The basic synthesis problem is discussed, and three analytical (modal synthesis, ruze synthesis, and spherical wave synthesis) techniques used. It is found that the theoretical beamshape can be optimized to given an absolute gain of 20.7 db at edge of coverage (8.8 deg from boresight). Three alternative antenna configurations (front-fed shaped reflector, circular array of helices, and hybrid) are considered. A C-band scale model of the proposed antenna configuration is detailed. Preliminary range tests show a strong reflector feed interaction which has the effect of an RF performance. Solutions are proposed to overcome this difficulty and to obtain an improved RF performance. The effects of reflector profile errors and reflector cut-outs on antenna electrical performance are analyzed.