Optimization studies of multiple beam antennas for EHF satellite communications

The design of multiple-beam antenna (MBA) systems for EHF communication satellites involves tradeoff studies of coverage gain, sidelobe level and beamwidth as a function of the number and sizes of the lens aperture and the feed directivity. The author defines those parameters that are common to any MBA system. Results are presented of parametric studies in which the lenses are assumed to be simple apertures with ideal transducers that convert the spherical wavefront from the feed into a plane wave without introducing any aberrations. An 18 in. diameter zoned dielectric lens for a 271 beam MBA was fabricated and tested with a Potter feed horn, both with and without resistive tapering. Measurements of its on-axis radiation patterns and gain show that they are correctly predicted by the aperture theory used for optimization. These results indicate that optimum dimensions for a lens or reflector MBA may be determined through straightforward analytic techniques and the use of the parametric curves.<>