Synthesis of shaped beam reflectarrays with constrained geometry by exploiting nonradiating surface currents

The design of reflectarray surface currents that satisfy both radiation and user-defined geometry constraints is addressed by means of a novel methodology that takes advantage of the nonuniqueness of electromagnetic inverse source (IS) problems. Toward this end, the reflectarray current synthesis is formulated as an IS problem, and its nonradiating current components are profitably exploited as additional design degrees of freedom. As a consequence, an analytic solution, which does not require any iterative local/global optimization and inherently fits both radiation and geometry constraints, is derived. The features and the potentialities of the proposed approach are assessed throughout the selected numerical experiments dealing with different (type/size) reflectarray apertures and various (shape/dimension) forbidden regions.