Ensuring global coverage with isophoric direct radiating ring arrays

In this contribution we discuss the feasibility of a full-Earth coverage from GEO satellite by means of isophoric (that is, equi-amplitude) Direct Radiating Arrays (DRAs). By focusing on the ring-array architecture we show that a large beam scanning requirement imposes some severe geometrical constraints on the final array layout. Furthermore, we introduce a synthesis procedure capable to generate arrays satisfying the desired specifications with a reasonably low number of control points.