Shaped-beam antenna design considerations for high power broadcasting satellites

In order to achieve better service quality than that of the present satellites, a novel technique is described to design a multiple-horn type circularly polarized shaped-beam antenna as a possible candidate for a next generation large scale high power broadcasting satellite. WARC-BS related antenna requirements, such as a spill over power of both copolar and cross-polar components radiated outside the service area, are considered on the basis of power flux density on the earth assuming the antenna input power of 200 W. In order to transmit more satellite power to more densely populated cities, the service area is split into five regions where the shapes of the split regions, each covered by the five antenna beams, are different from each other. A corrugated conical horn with elliptical aperture is used as a main feed horn to illuminate an offset paraboloidal reflector with circular aperture to cover an elliptical main region. In order to make the beam separation distances between the feed horns short, pyramidal horns with crossed rectangular apertures are used which cover the other regions in the service area.